Under The BridgeUnder The Bridge

Musings
Swift Pitfalls: Here Be Dragons

It’s always exciting to live through a period of exploration and evolution, isn’t it? A bit too exciting at times, you might think. Here’s a collection of subtleties you might run into out in the unexplored regions of the new ecosystem, particularly on the Objective-C borderlands where the ground is treacherous and monsters roam:

Surprises with Swift Extensions

Today, we received a report for a very weird crash with a stack trace that contained only UIKit symbols, but was clearly triggered by a specific action in PSPDFKit…

… That was it. These seemingly innocent extensions were overriding private API. Apple’s private API detection is not super sophisticated and wasn’t triggered when the app was uploaded to the App Store. It’s also not a public symbol so there were no warnings, not even a log message. Unprefixed categories are always dangerous, especially on classes that you do not own, like UIViewController. In PSPDFKit, we use categories for shared code, but prefix any method with pspdf_ to be absolutely sure we do not hit any name clashes. It’s certainly not pretty, and prefixes in Swift look even more alien, yet as you can see in this bug hunt, they are definitely necessary.

The whole story is worth a read, if you haven’t run into the overriding private API problem before — especially not of the “crash immediately on launch with the new OS point release” variety, but that’s another story altogether — or you can just cut to the chase with

tl;dr: Swift extensions on Objective-C classes still need to be prefixed. You can use @objc(prefix_name) to keep the name pretty in Swift and expose a prefixed version for the ObjC runtime.

To Optional or Not to Optional: IBOutlet

“When you declare an outlet in Swift, you should make the type of the outlet an implicitly unwrapped optional … When your class is initialized from a storyboard or xib file, you can assume that the outlet has been connected.” — Using Swift with Cocoa and Objective-C, Apple

… Except in practice there are tons of edge cases in the lifecycle of a view controller where this simply isn’t true. And what happens when you try to access emailField when the view isn’t loaded for some reason? The app crashes…

UIKit was written during the era of nil messaging, and I’ve come to realize it isn’t safe to 100% assume IBOutlets can’t be nil. Going forward I’ll be using optionals for my IBOutlets. I have a task in my bug tracker to scrub all my IBOutlets to covert them from implicitly unwrapped to standard optionals. A few extra question marks never hurt anyone; I’d rather my app not crash.

Some more discussion of appropriate outlet semantics in Outlets: Strong! Or Weak?

Seven Swift Snares & How to Avoid Them

⚠ Double-check attribute names that override protocol extensions.

⚠ For every attribute defined in a protocol extension, declare it in the protocol itself.

⚠ Do not extend an imported protocol with a new attribute that may need dynamic dispatch.

⚠ Avoid extending a protocol with a restriction if the new attribute might need dynamic dispatch.

⚠ Avoid assigning the result of an expression with side-effects to left-hand-side with optional chaining.

⚠ Avoid in-out parameters in closures.

⚠ Avoid currying with in-out parameters because the code will fail if you later change it to explicitly create a closure.

Be careful out there!

h/t: iOS Dev Weekly!

UPDATES:

Swift Golf

Hipster Swift: Demystifying the Mysterious

10 Swift One Liners To Impress Your Friends

10 Tips when moving from Objective-C to Swift

Swift Mistakes I’ve Made – Learning Swift Best Practices

Implicitly Crashing Optionals

Avoiding the overuse of @objc in Swift

Swift With Two Twos!

It’s update day! New iOS 9.3, OS X 10.11.4, Xcode 7.3 (+ Alcatraz 1.17), and … Swift 2.2! Time to check out the latest changes — and to perk up your heart rate just a little bit, it’s “mostly source-compatible with Swift 2.1”. Which is true, but be prepared for many selector-related warnings:

We are very pleased to announce the release of Swift 2.2! This is first official release of Swift since it was open-sourced on December 3, 2015. Notably, the release includes contributions from 212 non-Apple contributors — changes that span from simple bug fixes to enhancements and alterations to the core language and Swift Standard Library.

Language Changes

Swift 2.2 is a minor language release that is mostly source-compatible with Swift 2.1. It contains the following language changes that went through the Swift’s evolution process:

Beyond these language changes Swift 2.2 also contains numerous bug fixes, enhancements to diagnostics, and produces even faster-running code…

Details on those bug fixes and diagnostics at swift/CHANGELOG.md and in the Xcode 7.3 release notes. Good discussion of the important changes over at hackingwithswift.com too:

What’s new in Swift 2.2

Naturally, those on top of things objc.io folk have their latest magnum opus Advanced Swift ready to go with 2.2 now, which looks like a worthwhile read: check out the online preview.

UPDATES:

New Features in Swift 2.2

Parse Drops the BaaS

So the veritably seismic news of the week, should you rely on Parse for mBaaS services, is their pulling a StackMob:

We have a difficult announcement to make. Beginning today we’re winding down the Parse service, and Parse will be fully retired after a year-long period ending on January 28, 2017. We’re proud that we’ve been able to help so many of you build great mobile apps, but we need to focus our resources elsewhere…

If you think hosted services are a business opportunity, here’s source for a head start :

Parse Server was built in Node.js and works with the Express web application framework. It can be added to existing web applications, or run by itself. Check out the server and migration guides here, the open-source repository here, and the example project here. We encourage you to provide bug reports and feedback via the GitHub issues on the Parse Server repository. There’s even a developer wiki, which can be found here.

Nearly everything you’ll need for your app is supported in Parse Server, with the main exceptions of Push delivery, Analytics, and Config…

So that’s something. For a great roundup of rants and insights on just how little that something is, head over to Michael Tsai’s and check out Sunsetting Parse. All worth reading to share the pain, but here’s some particularly good giggles:

Guy English:

If it had been me shutting down Parse I would have changed the home page to not point out how many “Trust Us”.

Jeff Lawson:

“But seriously developers, trust us next time your needs temporarily overlap our strategic interests. And here’s a t-shirt.”

Joel Bernstein:

The subtext to the Parse shutdown is “never trust a Facebook platform ever again, for any reason”

Feel the burn!

Moving on, you can always take Marco Arment’s advice:

For whatever it’s worth, running your own Linux servers today with boring old databases and stable languages is neither difficult nor expensive. This isn’t to say “I told you so” — rather, if you haven’t tried before, “You can do this.

But if you’d really, seriously, rather not have to add maintaining your own backend to your load, there’s a crowdsourced list here that looks good:

ParseAlternatives: A collaborative list of Parse alternative backend service providers.

Current categories are:

Personally, we’d like to try out CloudKit one of these days…

UPDATES:

iOS Dev Tools: Backend Services

How To Migrate Your App And Protect It From Shutdowns Like Parse’s

Top 5 Parse Alternatives

Migrating My Data From Parse

AppCoda.com Parse series:

Deploying Parse Dashboard

Parse Server: A Viable Open Source Platform?

Parse Server – 100 days later

Migrating to Parse Server: Adventures With Heroku and Why We Broke Up

Parse Server Tutorial with iOS

The Grand Opening

So, just in case you spent the weekend being dead — and probably didn’t miss it even if you were — Swift.org is a thing!

And unlike previously accustomed source dumps, this is going to be the working repo going forward:

“The Swift team will be developing completely in the open on GitHub,” Federighi told Ars. “As they’re working day-to-day and making modifications to the language, including their work on Swift 3.0, all of that is going to be happening out in the open on GitHub.”

Open, indeed — to general surprise, the entire commit history of Swift went public; check this visualization out:

Over 5 years of work, 23,000+ commits condensed into 8 minutes

Rather interesting is the focus in bringing Swift to the cloud. There’d been these Perfect people,

Wouldn’t it be amazing if you could develop every aspect of your apps, front and back end, all using Swift™? We think so. That’s the vision behind Perfect. Perfect is the first enterprise-grade web server and web toolkit for the Swift programming language…

which looked like a rather … selective … interest. But that’s not what Apple thinks:

“IBM has been a major source of that feedback for us, and they’ve been eager since they got started with Swift, saying “how can we take these applications we’re writing for enterprise all the way from the mobile platform into the cloud?” …

Where we expect the community to really push is the cloud framework, and we think there will be a lot of energy to adapt Swift into the datacenter…

And why yes, IBM is right out of the gate with support for Swift, in your browser no less:

Today, IBM introduced an online 2.2 Swift Sandbox. John Petitto writes, “We love Swift here and thought you would too so we are making our IBM Swift Sandbox available to developers on developerWorks.”

Another Swift browser REPL is at Swiftstub.com.

Well, the idea that community participation will drive adoption might work out, and might not, but we know one thing for sure in less than a week:

Swift’s comments and test suite are on track to be one of the most correctly spelled and best indented ones in the industry! 🐙🐱

Indeed. If you can’t find any more speling misteaks and feel like getting in on the Linux development action, here’s a great start:

Introduction to Open Source Swift on Linux

In this tutorial, you’ll set up a Linux environment on your Mac, install Swift, and compile and run some basic Swift examples on Linux. Then you’ll take stock of the new bits offered by Apple, and finish off with a look into into the misty crystal ball of time, and guess what this all means for the future…

Oh, that’s not hard to guess, is it now?

And here’s some more suggestions for getting involved:

  • Search for FIXME in the code base and make the fix – @ayanonagon
  • Add more Unit Tests (something I wrote down as my personal strategy) – @KostiaKoval
  • Fix bugs! Yes, Swift bugs are tracked publicly via Jira!
  • As many have noticed, the Foundation Project has a lot of NSUnimplemented(). Instead of complaining (or worse, laughing about it), contribute to it! The nice things is that it’s in Swift – you don’t need to know C++. Here is a great example PR from @simjp!
  • For larger changes, write a proposal and ask for reviews from the community – amazing example by @ericasadun

As Jesse Squires said it the best: Let the revolution begin!

Pencil This In

Managed to get your Apple Pencil delivered yet? If you have, and you’ve gone through some introductory tutorials, here’s a remarkable burst of creative applications from the redoubtable FlexMonkey for you to try out:

PencilScale – Using an Apple Pencil with an iPad Pro as an Electronic Scale

Following all the interest created by my Plum-O-Meter, I couldn’t resist trying a similar experiment with my newly arrived Apple Pencil, so here’s PencilScale, an iPad Pro application that uses the Pencil as an electronic scale … The update() method simply subtract’s the touch’s force from a base weight (which is set as the current touch force when the ‘zero’ button is pressed) and multiplies it by 140 which gives the weight in grams (very roughly) …and amazingly, that is pretty much all there is to it!

PencilController – Using Apple Pencil as a 3D Controller for Image Editing

My PencilController project is a Swift app for iPad Pro that applies two Core Image filters to an image: a hue adjustment and a colour controls which I use to control the saturation … The hue filter’s value is controlled by the azimuth angle and the saturation is controlled by the altitude angle: when the pencil is vertical, the saturation is zero and when it’s horizontal the saturation is eight (although when the pencil is totally horizontal, its tip isn’t actually touching the screen, so the highest saturation the app can set is about six and three quarters).

PencilSynth – An Apple Pencil Controlled Synthesiser

PencilSynth is an AudioKit powered synthesiser (mis)using the Pencil as a joystick controller. It’s based on AudioKit’s TouchRegions demonstration and works like this:

  • The Pencil’s horizontal position on the screen defines the output frequency
  • The Pencil’s vertical position on the screen defines the output modulating multiplier
  • The Pencil’s altitude angle defines the output carrier multiplier
  • The Pencil’s azimuth angle defines the output modulation index

FurrySketch: Hirsute Drawing with an Apple Pencil

I thought it was about time to play with the Pencil for its intended purpose, sketching, and see how I could use its orientation data to affect brush strokes.

FurrySketch is a Pencil powered drawing application that draws a sort of multicoloured hair and, most excitingly, the hair’s direction matches the angle of the Pencil. It was super simple to write and, at least in my opinion, gives really nice results … If you are writing drawing apps, adding Pencil support is not only super easy, it adds real value for your users. The technique I’ve used here to draw hair is only a few lines of code way from spray cans and air brushes and I genuinely believe the iPad Pro will prove to be an amazing device for creatives.

Seen any other creative applications? Let us know! And if you’re still pondering over getting one, check out Gus Mueller’s love letter:

The Hype is Real

Every single stylus that has been made for the iPad or iPhone has been a pile of dog shit when compared to what you can do with a Wacom tablet. Even compared to what you could do 20 years ago with a Wacom tablet. The KoalaPad on an Apple //e was probably better.

It’s been hard, and upsetting. And so much money wasted on crappy iOS styluses. I stopped paying attention whenever a new stylus was announced, since I was inevitably let down.

And then this week I got the Apple Pencil (which is Apple speak for a stylus) and an iPad Pro. This new tablet from Apple has the hardware support needed to make a useful stylus. Hardware support that has been missing for five long, very long, agonizing years.

And It’s God Damn Amazing.

It feels absolutely right. Super low latency, palm rejection, and … it just works.

UPDATES:

Scribe: A Handwriting Recognition Component for iOS

BristlePaint: Embossed Painting with Individual Bristles using SpriteKit Normal Mapping

Smooth Drawing for iOS in Swift with Hermite Spline Interpolation

Apple Pencil Controlled Christmas Tree Bowling with SceneKit

Apple Pencil Tutorial: Getting Started

Playground Power

There’s a new article for your attention up at the official Swift blog, Literals in Playgrounds:

New in Xcode 7.1 is the ability to embed file, image, and color literals into your playground’s code. Literals are the actual values of your data represented in their native format, directly within the Xcode editor. For instance, there’s no need to type “myImage.jpg” in the editor – just drag your image from the Finder and the actual image will appear in-line with your code. Instead of showing RGB values to indicate color, the playground will render a color swatch. Literals in playgrounds behave similarly to code you would otherwise hand-author in regular Swift code, but are rendered in a much more useful manner…

If you’ve been underutilizing those playground thingys so far, Playground Secrets and Power Tips is literally a great way to get up to speed,

cover-216x300.jpg

and it’s literally up to the minute:

So what’s new in this edition? I’ve done a back to front update to incorporate all the new XCPlayground features in Xcode 7.1 beta 3: the new liveView feature that can be used with views and view controllers (and the XCPlaygroundLiveViewable protocol that supports rendering arbitrary model objects), the new ways to continue execution and capture values, etc.

Also, you’ve probably noticed the move to Markdown this year for playground documentation and Swift Documentation, but now there’s full documentation over at the mothership:

Markup Formatting Reference

Use markup formatting commands to create rich comments in playgrounds and to document your Swift symbols for Xcode quick help. Commands include page level formatting for headers and other elements, inline formatting, and images. Playground formatting commands enable page navigation as shown in the following figure … Swift symbol documentation adds descriptions to symbol completion and quick help for symbols …

So if you’re using those legacy HeaderDoc conventions, why there’s all you need to level up!

And to finish up, perhaps a potpourri of playground posts of particular perspicuity:

General tips: NSHipster’s XCPlayground and Erica Sadun’s multitudinous tidbits

Performance Testing in Xcode Playgrounds: “playground that has a similar function to the “measurePerformance” function in XCT.”

Core Graphics Tutorial Part 3: Patterns and Playgrounds: “draw it in a Swift Playground, and then copy the code to a UIImageView subclass.” Or, Overlooked playground cool stuff #3: “build, preview, and save the image to disk. Perfect for creating masks and labels.”

Swift-Diagram-Playgrounds: “two different approaches to creating Diagrams as value types.”

Numerical Algorithms using Playgrounds: “solve problems that don’t have an analytic solution.”

UPDATES:

Little Bites Of Cocoa:

Xcode 7.3 Beta 2 introduces live interactive playgrounds; Interactive Playgrounds

Gameboard: “Gameboards built in a playground.”

XCTestPlayground: “… a simple implementation of most XCTAssert macros to use in a Playground … I use this to do TDD directly inside a Playground and then move the code as-is inside my test files.”

Using a Core Data Model in Swift Playgrounds

To The Nines

Happy iOS 9 Day! Check out all the good stuff announced over at RayWenderlich.com:

This year marks our 5th annual iOS release celebration: the iOS 9 Feast. The iOS 9 Feast consists of 9 courses:

  • Appetizers: Beginning UIStackView & tvOS Tutorials
  • First Course: iOS Apprentice Fourth Edition
  • Second course: iOS Animations by Tutorials Second Edition
  • Third course: Core Data by Tutorials Second Edition
  • Fourth course: iOS 9 by Tutorials
  • Fifth course: watchOS 2 by Tutorials
  • Sixth course: Swift Apprentice
  • Seventh course: 2D iOS & tvOS Games by Tutorials
  • Eighth course: iOS 9 Tutorial Month
  • Dessert: iOS 9 Feast Giveaway

During the iOS 9 Feast, we’ll help you get fully up-to-speed with iOS 9, Swift 2, tvOS, and watchOS 2 development, no matter how you prefer to learn. You’ll learn about UIStackView, iOS 9 Search APIs, Swift 2 error handling, GameplayKit, and much more.

Plus, we have over $18,000 in giveaways for lucky readers – our biggest giveaway yet!

Other tutorial sites worth a look are Hacking With Swift’s iOS 9 collection and the iOS 9 Day-by-Day series:

And here’s various subtleties worth knowing about:

Shipping an App With App Transport Security

There’s already been lots of great discussion about how ATS works – see, for example, Neglected Potential’s Working with Apple’s App Transport Security. Apple has also provided a descriptive tech note on the feature, clearly documenting the expectations of ATS and the exceptions that remain available to developers. And the community has noted in several articles that turning ATS off entirely is generally a Bad Idea.

This article is aimed at a different purpose: to look at the different speed bumps that can show up while building an app alongside ATS, and to explain how to get around them…

Also see Michael Tsai’s roundups App Transport Security and Shipping an App With App Transport Security.

How iOS 9’s Safari View Controller could completely change your app’s onboarding experience

With Safari View Controller, we now will have a way to “talk” to our webpage and learn a little bit about who the user is, and what they were doing, so we can do all of the following:

  • If the user already is logged into the website, you can seamlessly sign them in…
  • If they are not logged in, tailor the onboarding experience for that specific user…
  • Or, if you want to get fancy, you can even change the “intro” UI to be based on which kind of marketing the user came in from…

iOS: You’re Doing Settings Wrong

One of the apparently less known features for iOS 8 and above is the ability to deep link the user into Settings, where they can enable their Location, Notifications, Contacts, Camera, Calendar, HealthKit, etc for your app as needed…

…this gets even better in iOS 9! The Settings screen will have a back button to take the user directly back into your app! Seriously, there is absolutely no excuse to NOT use this.

Get Your App Ready for iOS 9

… iOS will now send out a notification, NSProcessInfoPowerStateDidChangeNotification, when the system enters or leaves low power mode. You can also query the current power state at any time by checking [[NSProcessInfo processInfo] isLowPowerModeEnabled].

If you have any points in your app where you might be able to save some power it’s now a good idea to check the power state and respect the user’s request to help save their battery.

Querying URL Schemes With canOpenURL

… If you build and link against the iOS 9 SDK you need to whitelist the schemes your app will query. What is important to understand is that this policy can also impact older Apps that have not yet been rebuilt with the iOS 9 SDK…

And top off your iOS 9 saviness by checking out this list of clever people and their clever tips!

Top Tips for iOS 9 Development: 12 Community Tips to Get Your App Ready for iOS 9

UPDATES:

iOS-9-Sampler: “Code examples for the new features of iOS 9.”

Advanced Touch Handling in iOS9: Coalescing and Prediction; ForceSketch: A 3D Touch Drawing App using CIImageAccumulator

Add iOS 9’s Quick Actions shortcut support in 15 minutes right now!; Lessons learned with 3D Touch; Developing With 3D Touch; Your 3D Touch Spirit Guide; Adding 3D Touch Quick Actions; Peek & Pop; 3D Touch Peek and Pop; Exploring Apple’s 3D Touch; 3D Force Touch: beyond peek & pop; 3D Touch in Swift: A Retrospective; Turning the iPhone 6s Into a Digital Scale; 3D Touch Introduction: Building a Digital Scale App and Quick Actions; The Next Step for 3D Touch; The Trouble With 3D Touch

Getting Started with Search APIs and SFSafariViewController in iOS 9; iOS 9: Getting Started With SFSafariViewController

A First Look at Contacts Framework in iOS 9

Support Universal Links; iOS 9 Universal Links & Forgotten Passwords; iOS 9.2 Deep Linking Guide: Transitioning to Universal Links

iOS 9 Multitasking Tutorial

What’s New in Storyboards?; Secondary Views in Interface Builder’s Storyboards

Xcode Transformers – Settings In Disguise

We’re great fans of .xcconfig files and other textua Xcode build process manipulations around here, and here’s some handy undocumented feature tips for you:

Xcode Build Setting Transformations

Xcode supports the ability to substitute the value of build settings using the $(BUILD_SETTING_NAME) or ${BUILD_SETTING_NAME} syntax in a number of places including Info.plists, other build setting values, and .xcconfig files. In these substitutions it’s also possible to add operators that transform the value in various ways. You may have seen one of these in the Info.plist included in project templates:

com.company.$(PRODUCT_NAME:rfc1034identifier)

This results in the value of the PRODUCT_NAME build setting being transformed into a representation suitable for use in the reverse DNS format used by CFBundleIdentifier. So if PRODUCT_NAME is “Whatever App” the resulting string is “com.company.Whatever-App”.

These transformations can be quite useful but don’t appear to be documented, so here’s the list of available operators and what they do…

Note that these operators can be chained, so you can do things like $(PRODUCT_NAME:lower:rfc1034identifier) or $(CONFIGURATION:upper:identifier).

Be sure to bookmark that for next time you’ve got some manipulating setup to do!

h/t: Michael Tsai!

UPDATES:

Sam Marshall writes lots of Xcode-related goodies, check out particularly

The Unofficial Guide to xcconfig files; Managing Xcode; Using Xcode Targets

Convenient Build Settings

Stencil Xcode Plugin “is an Xcode plugin that provides the ability to create custom file templates and use them in your project to create new files groups.”

SwiftLint: “A tool to enforce Swift style and conventions.”

Setting up SwiftLint on Travis CI

“Watch Your Language!”: The Road to Cleaner Code with SwiftLint

SwiftLint Doing Its Best To Ease Conflict

Using SwiftLint and Danger for Swift Best Practices

Xcode Search: the Hidden Gems

Change your API endpoint/environment using Xcode Configurations in Swift

Threading Safety First

Now this is a truly epic investigation of the evolution of how to write a singleton in Swift:

THE RIGHT WAY A.K.A. “THE ONE LINE SINGLETON (NOW WITH PROOF!”)

We knew about this “right” method of writing singletons, but we had no proof to back up our reasoning other than postulation … So I decided to do something about it and wrote up every way of initializing a singleton and inspected them at runtime using breakpoints. After analyzing each stack trace for any similarities I came across something interesting – PROOF!

*mic drop*

There’s been a number of other good posts lately in the area of threading and memory safety; we recommend checking out

Atomics in Objective-C

This post talks about the use of OS low level atomic functions (compare-and-swap, fetch-and-increment) to achieve both wait and lock free, thread-safe concurrent algorithms in your iOS/OSX apps.

It introduces a few classes that abstract away the gory details of some of the atomic functions made available by libkern/OSAtomic.h into conceptually simpler components that use Foundation types…

Strong, Weak, and Unowned – Sorting out ARC and Swift

I wanted to stop being unsure about the implications of typing one of those three words before variable / constant declarations, so I finally pulled up the Apple Documentation on ARC and began trying to digest the semantics. This article is an attempt to share what got sorted out in my brain as it regards ARC and Swift…

“Weak, Strong, Unowned, Oh My!” – a Guide to References in Swift

I often find myself worrying about retain cycles in my code. I feel like this is a common concern amongst others as well. I don’t know about you, but it seems like I am constantly hearing “When am I supposed to use weak? And what the hell is this ‘unowned’ crap?!” The issue we find is that we know to use strong, weak, and unowned specifiers in our swift code to avoid retain cycles, but we don’t quite know which specifier to use. Fortunately, I happen to know what they are AND when to use them!

Demystifying Retain Cycles in ARC

Retain cycles in ARC are kind of like a Japanese B-horror movie. When you start as a Cocoa/Cocoa Touch developer, you don’t even bother about their existence. Then one day one of your apps starts crashing because of memory leaks and suddenly you become aware of them, and start seeing retain cycles like ghosts everywhere. As the years pass, you learn to live with them, detect them and avoid them… but the final scare is still there, looking for its chance to creep in.

Tip: Avoid retain cycles without doing the strong to weak dance by passing block parameters instead of remembering to capture weakly.

And Grand Central Dispatch helper frameworks in Swift seem to be quite a thing lately; here’s some for you to check out:

Async: “Syntactic sugar in Swift for asynchronous dispatches in Grand Central Dispatch.”

Eki: “is a framework to manage easily concurrency in your apps that wraps the powerful API Grand Central Dispatch”

GCDKit: “Grand Central Dispatch simplified with Swift.”

iDispatch: “Easy to use wrapper over GCD for iOS.”

KillerRabbit: “THGDispatch module, includes GCD bits such as Queues, Groups, Timer, Semaphore, etc.”

UPDATES:

Throttle: “Lately I have been really interested in the AdvancedNSOperations talk given at WWDC last year. This talk and the awesome sample project released with it, kind of opened my eyes to the power of NSOperations..”

Queues are not bound to any specific thread

GCD’s Main Queue vs. Main Thread

Mutexes and closure capture in Swift

Linux Swift Too!

TL;DR: You can download The Swift Programming Language now, or read online here — go straight to the diffs if you wish!

So you all happy now, we trust? The open sourcing we’d figured had to be coming, but contributing a Linux port of Swift 2.0? That was a bit more so.

Here is what we can tell you so far:

  • Swift source code will be released under an OSI-approved permissive license.
  • Contributions from the community will be accepted — and encouraged.
  • At launch we intend to contribute ports for OS X, iOS, and Linux.
  • Source code will include the Swift compiler and standard library.
  • We think it would be amazing for Swift to be on all your favorite platforms.

We are excited about the opportunities an open source Swift creates for our industry. Baked-in safety features combined with excellent speed mean it has the chance to dramatically improve software versus using C-based languages. Swift is packed with modern features, it’s fun to write, and we believe it will get used in a lot of places. Together, we have an exciting road ahead…

Swift On The Server being the next destination there, we’d say that Linux-port bit is a pretty darn clear declaration of.

And of course, here we go with MOAR REWRITES:

An advanced error handling model provides clear, expressive syntax for catching and throwing errors. It’s also easy to create your own custom error types so you can describe error cases with clear, meaningful names…

New syntax features let you write more expressive code while improving consistency across the language…

  • Powerful control flow with do, guard, defer, and repeat
  • Keyword naming rules unified for functions and methods
  • Protocol extensions and default implementations
  • Extended pattern matching to work in if clauses and for loops

Release notes for the new OSes are interesting too:

And here’s your list of WWDC Session sample code of assorted niftiness.

More collected links and details by Erica Sadun at What you need to know, and no doubt there’ll be plenty of in depth analysis to collect … swiftly!

UPDATES:

New stuff from WWDC 2015

ASCIIwwdc.com: Searchable full-text transcripts of WWDC sessions

NSHipster’s iOS 9

Ray Wenderlich’s WWDC 2015 Initial Impressions; What’s New in Swift 2

Michael Tsai’s WWDC 2015 Links

Top 10 WWDC 2015 Videos

Changes to the Swift Standard Library in 2.0 beta 1; Swift Diffs

Swift v2.0 Error Handling – Revisit; Swift 2: Test Driving the Error Handling; Swift 2 error handling in practice; Keep your Swift Exceptions clean, easy to update and future proof; Lets try! Swift(version: Swift.2); Thoughts on Swift 2 Errors; Swift Exceptions are Swifty: Part 1; Error Handling in Swift 2.0; Everything You Should Know About Error Handling in Swift 2.0 (but Were Too Afraid to Ask); Swift 2.0 Error Handling; Thoughts on Swift 2 Errors

Notes from WWDC 2015: Failing Gracefully: Swift 2.0 Error Handling; Swift 2 Error Handling, Continued

Swift 2.0: Day One (do-try-catch)Closures that Throw: Rethrows in Swift 2.0; Throw What Don’t Throw; Re…throws?

Swift 2 + Xcode 7: Unit Testing Access Made Easy!!!!; Improvements to Unit Testing in Swift with Xcode 7; Test Logs in Xcode

Swift 2 – What’s new; Swift 2: The overview; Other New Swift 2 Features

What’s New in Swift 2: repeat-while, guard, defer, ErrorType, OptionSetType, multi-payload enums, if-case, for-case, #available, try!

Notes from WWDC 2015: The Enumerated Delights of Swift 2.0 Option Sets; Exploring Swift 2.0 OptionSetTypes

Exploring Swift 2 Protocol Extensions; Protocol-Oriented Programming is Object-Oriented Programming; The ♥ of Swift; The Ghost of Swift Bugs Future; Introducing Protocol-Oriented Programming in Swift 2; Swift protocol extension method dispatch; Swift Protocols; Swift Generic Protocols; Swift’s Protocol Extensions: A Practical Example

The Genius of Swift 2’s defer; guard & defer

Func Parameters in Swift 2.0Parameter Defaults and Optional Function Parameters in Swift 2.0

Friday Q&A 2015-06-19: The Best of What’s New in Swift

Friday Q&A 2015-07-17: When to Use Swift Structs and Classes

C Callbacks in Swift

Swift 2, Beta 2

Protocol extensions and the death of the pipe-forward operator

Swift 2: SIMD

Similarly different: join(), reduce() and flatMap() in Swift 2

Every Swift Value Type Should Be Equatable; Notions of Equality in Swift

Objective-C in 2015: “Swift 2 isn’t the only shiny new toy.”

Changes to the Swift standard library in 2.0 betas 2..<5

Strings in Swift 2: “In Swift 2, the String type no longer conforms to the CollectionType protocol…”

Understanding flatMap; Map and Flatmap; What do map() and flatMap() really do?; Map and FlatMap Demystified; map all the things!; map & flatMap

Linked lists, enums, value types and identity

Mixins and Traits in Swift 2.0

Nil vs throwsNils vs Throws in #swiftlang Part II

Practical Swift: pages generator – build once, use many

Swift + Guard: Syntactical Sugar Pt.2

Swift 2 Pattern Matching: Unwrapping Multiple Optionals; Match Me if you can: Swift Pattern Matching in Detail; Swift 2: Control Flow Pattern Matching Examples; Pattern Matching in Swift and Ranges and Intervals in Swift and More Pattern Matching Examples; Tuples + Pattern Matching

Swift 2 Beta 6; Up the mix with Beta 6; How to Print: the Beta 6 edition

Swift 2.0: Let’s try?; How to “try?” (Yoda alert); Swift + Error Handling Syntactical Sugar Pt.3; Error Handling: From Objective-C to Swift and Back; Let it throw, Let it throw!

Swift-Community-Best-Practices

Initialization in Swift

Swift 2.1