Under The Bridge Under The Bridge

Category: iPhone
Tip: Check Your Layout Privilege

On the off chance you haven’t bothered to read carefully the 8.3 point release notes, having been busy fixing up your broken Swift code and all, there’s a subtle time bomb lurking therein for next time you get it building again:

When linking against iOS 8.3, any code that relies on layout information (such as the frame) of a UIButton subview when the button is not in the window hierarchy will need to send layoutIfNeeded to the button before retrieving layout information (such as button.titleLabel.frame) to ensure that the layout values are up to date.

For example, if you had something like this:

You now need:

Yikes. Not sure if there’s any currently in development, but we’ve certainly used and/or written ourselves many pieces of code of that form that are now problematic. Probably a sound plan to audit all your button-creating code … just in case.

h/t: @sanjeetsuhag via @mariozullo!

UPDATES:

Looks like layout’s got some pretty serious under the hood revisions: for instance this example

If you construct layout constraints manually … pass in nil for the second view, and that contradicts the the attribute being specified, you’ll now get an exception. Previous OS releases appear to have quietly ignored this transgression on your code’s part.

So yep, better give all your layout stuff a good checking under 8.3. It’s the only way to be sure.

Adaptability Changes in iOS 8.3

“IB started respecting the “relative to margin” option for constraints starting in 8.3” may explain your cells looking different.

Thrash Metal

Since all you Dear Readers seemed to think our Daft Punk allusion last post was clever, let’s do another music callout this time. Not that it really takes a whole lot of clever to connect up Metal with a particularly extreme genre of such, but hey, it gives us an excuse to link to the thrashiest of thrash bands playing the Duke Nukem theme for your post-reading background music, which we just haven’t done enough of so far.

Any-ways, in case like us you’d pretty much skipped over stuff about Metal figuring it was only of interest to game engine writers, there’s some interesting stuff around that people are doing with it you might like to be aware of. In particular, this FlexMonkey post caught @NatashaTheRobot‘s eye (and if you’re not subscribed to her Swift newsletter, you should be):

Two Million Particles at 25 Frames Per Second on an iPad

Following on from my last post where I managed to calculate and render over 1,000,000 particles in realtime, I’ve done some pretty effective tweaking of the code to create an app that calculates and renders (with blur and trails) over 2,000,000 particles at around 25 frames per second on my iPad Air 2…

Not bad, not bad. Also note followup:

Swarm Chemistry: Creating an Advanced GPU Based Particle System with Metal

…With Metal, I’ve been able to create a kernel shader that can calculate and render 4,096 swarm members at 30fps – so that’s 16,777,216 particle interactions per frame or 503,316,480 particle interactions per second! Pretty impressive stuff for a tablet computer!

Code at FlexMonkey / MetalParticles, with UI described in Adding a User Interface to my Swarm Chemistry App on an iPad

So that’s pretty cool, but still a little niche. A good number of you probably run into need for parallel computation, particularly image processing, not all that rarely though, yes? Start over at Metal-dedicated site Metal By Example and check out these articles:

Introduction to Compute Programming in Metal

This post is an introduction to topics in compute (or data-parallel) programming. It is designed to be read before its companion article, Fundamentals of Image Processing. In this article, we will cover the basics of setting up the compute pipeline and executing kernel functions on large sets of data in parallel…

Fundamentals of Image Processing in Metal

In this post, we will start exploring the world of image processing with the Metal shading language. We will create a framework capable of representing chains of image filters, then write a pair of image filters that will allow us to adjust the saturation and blur of an image. The end result will be an interactive app that allows you to control the image filter parameters in real-time…

Back at FlexMonkey there’s a project FlexMonkey / MetalReactionDiffusion building off that described in these posts:

Metal Kernel Functions / Compute Shaders in Swift

Reaction Diffusion Cellular Automata with Metal Compute Shaders

Swift & Metal: 1,000 Reaction Diffusion Solver Iterations per Second

And as long as we’re mining for Metal nuggets here, if this has inspired you to go learn more about it from scratch, here’s some good intros:

Ray Wenderlich’s iOS 8 Metal Tutorial with Swift: Getting Started and Part 2: Moving to 3D

LiquidFun Tutorial with Metal and Swift – Part 1 and Part 2 and Part 3

objc.io’s Metal

An Introduction to 3D Graphics with Metal in Swift

If you want to get more into the rendering side than that, then check out all the rest of the articles at Metal By Example.

UPDATES:

iOS GPU Programming with Swift & Metal

Particles Set Free! High Performance Particles for Swift Developers

Audio Visualisation for iOS with AudioKit & ParticleLab

Rendering Text in Metal with Signed-Distance Fields

Swifter Swift Image Processing With GPUImage

Stream Video Textures into 3D Scene with Metal

The Supercomputer In Your Pocket: Metal & Swift

Understanding PowerVR GPUs via Metal

A Forest Of Loggers

So since we moved off Lightspeed Pascal as our Macintosh development environment way back in the day, we’ve been toting around this suite of logging, timing, and so forth debugging macros that by this time can be called transparently from .c/.cpp/.m/.mm files in development environments ranging from Lightspeed C through Metrowerks CodeWarrior up to Xcode 6+; but as we gear up to take on our intended New Year’s resolution of shipping a full hand of Swift apps next year … oh wait, there’s no macros in .swift code now! Well, there goes two and a half decades of accumulated cleverness out the window, bah humbug.

Not that it would be too terribly hard to rewrite said suite using NDEBUG and @autoclosure like assert(), but why bother with that when no doubt there’s somebody else’s projects for native Swift logging out there doing that already we can join? And why yes, here’s two that the exemplarily diligent ManiacDev folk have turned up on Github:

XCGLogger looks considerably more active than Swell, so we’ll go with that one. Unless any of you Dear Readers have an excellent reason why not. But long as we’re on the topic, let’s take a look at what Objective-C options checking CocoaPods brings up that we could raid for feature additions … my, there are a lot, aren’t there now?

  • CCLogSystem (5/54/18) “A Log system for iOS.Support print, record and review logs.”
  • CocoaLumberjack (270/4131/705) “A fast & simple, yet powerful & flexible logging framework for Mac and iOS”
  • DLLog (1/2/1) “NSLog-like logging API with support for level and context filtering”
  • GRLogger (1/2/1) “a logger utility for debugging and tracing”
  • LibComponentLogging (5/101/13) “Logging for Objective-C with log levels and log components.”
  • Log4Cocoa (12/80/29) “is a Log4j port for iOS and Mac OS X”
  • MTLog(11/218/24) (ManiacDev) “NSLog replacement for coders!”
  • NALog (1/3/0) “An easy, lightweight, and simple NSLog-based logging tool”
  • NBULog (13/22/5) “Log framework based on CocoaLumberjack…”
  • NSLogger (147/2447/299) “A modern, flexible logging tool”
  • NWLogging (7/14/4) “A minimalistic logging framework for Cocoa”
  • OCLogTemplate (8/9/3) “A flexible logging header for Objective-C”
  • TFLogger (7/2/0) “Dependency free logging library”
  • TULogging (1/7/0) “Better logging that uses ASL log levels”
  • UALogger (11/235/21) “A powerful and flexible logging utility for Mac/iOS apps”
  • WZLog (1/2/0) “A log system for iOS” … and that’s about it not in Japanese.
  • XLFacility (8/97/2) “Elegant and extensive logging facility for OS X & iOS (includes database, Telnet and HTTP servers)”

CocoaLumberjack is pretty much the venerably accepted standard, as the numbers there attest, but some of these othes look interesting too. Particularly that very last one, XLFacility; from the ManiacDev writeup,

Some of the features of XLFacility include:

  • Viewing of logging messages in real-time via Telnet or TCP
  • An HTTP server for viewing real-time log messagess and browsing past logging messages
  • Different logging levels, and macros for easy logging at each level
  • Customizable logging formats
  • An in-app logging overlay that can appear when messages are sent to XLFacility
  • A nice syntax for creating your own custom loggers

With XLFacility you can log to the console, a file, a SQLite database, and you can also view messages in realt-time via Telnet or TCP and there is a built-in http server so you can browse past log messages or see live updates…

That’s some serious feature-laden logging there, that is.

UPDATES:

ZHSwiftLogger: “…will use println() for development and use NSLog() for production.”

PrintlnMagic “An alternative for Swift’s println() function along the lines of DLog.”

SwiftLog “Simple and easy logging in Swift.”

Debug Logging In Swift

Teleport-NSLog: Open Source Library Enhancing NSLog Allowing You To Log To A Remote Server

CleanroomLogger: “provides a simple, lightweight and performant logging API written in Swift”

Learn How People Use Your App – an App Analytics Tools Round-up

ARAnalytics : “is a analytics abstraction library offering a sane API for tracking events and user data. It currently supports on iOS: TestFlight, Mixpanel, Localytics, Flurry, GoogleAnalytics, KISSmetrics, Crittercism, Crashlytics, Bugsnag, Countly, Helpshift, Tapstream, NewRelic, Amplitude, HockeyApp, ParseAnalytics, HeapAnalytics, Chartbeat, Yandex Mobile Metrica, and Branch. And for OS X: KISSmetrics and Mixpanel.”

ARAnalyticsLogger: “A bridge between CocoaLumberjack and ARAnalytics,” derived from CrashlyticsLumberjack

Aspect-Oriented Programming and ARAnalytics

Swiftalytics: “A declarative Swift DSL for your view tracking needs.”

SwiftyBeaver Tutorial for iOS: A Logging Platform for Swift

Prerelease App Store Testing

What, you say, aren’t “prerelease” and “App Store” definitionally contradictory? Why no, no in fact they are not!

How to Test the Final App Binary before It Is Released on the App Store

  1. Manually release the app…
  2. Submit your app for review as usual…
  3. Pending developer release…

… At this point the Promo Codes link appears at the bottom of the app details page.

And apparently promo codes can be requested and work just fine even when the app isn’t technically released yet! Aside from this small caveat:

… when the promo code is for an update, iOS sometimes gets confused. It’s not consistent. But sometimes the App Store app shows an Update button right after the download is complete. It’s not clear to me if tapping the Update button will download the update you really want, or if it will “update” to the latest public release available on the App Store. Sometimes the whole process fails and my update is nowhere to be seen. So don’t be dismayed if need to burn more than one promo code to get the binary you want downloaded onto your device…

Still, it’s pretty awesome to be able to do a final final final test that no showstoppers slipped through into the actual App Store binary and reduce your launch day stress by several orders of magnitude, tisn’t it now?

NSFileCoordinated iOS IPC

IOS IPC? For reals? Well, for a “your app group” definition of “P”, yep pretty much:

Sharing data between iOS apps and app extensions

You’ll want to use NSFileCoordinator any time you want to read or write your shared files. You’ll also want to implement NSFilePresenter any time you need to know if a file has changed. These were introduced as companions to iCloud, where both your app and the iCloud daemon might want to access the same file. They’re not iCloud specific, though…

There’s still no full IPC mechanism on iOS. NSDistributedNotification hasn’t made the jump from OS X to iOS and probably never will. But file coordination and presentation can serve the same purpose, as long as the apps use the same app group.

When I was adding file coordination and presentation to my demo app, I realized that they could also be used for notifications between an app and its extensions. If one of them does a coordinated write while the other is using a file presenter for the file, the call to presentedItemDidChange happens almost instantly. Notification is the whole purpose of that method, so it makes sense it would work this way. I want to be notified if a specific file changes, and that’s how I get the notification.

But you don’t need to care about the file contents to be interested in notifications. If you just want a notification, choose a file name and use it as the notification mechanism. Any time one process needs to notify the other, make a change to the file. The other will get a file presenter call, and the notification is complete. It feels sort of like a hack but really this is exactly how the API is designed to work.

Cool beans! That opens up the extension useful problem space a good deal, doesn’t it now?

h/t: Michael Tsai!

UPDATES:

Accessing Shared Data from an App Extension and its Containing App

Important: When you create a shared container for use by an app extension and its containing app in iOS 8, you are obliged to write to that container in a coordinated manner to avoid data corruption. However, you must not use file coordination APIs directly for this [UPDATE: in iOS 8.1.x and earlier]. If you use file coordination APIs directly to access a shared container from an extension in iOS 8.0 [UPDATE: in iOS 8.1.x and earlier], there are certain circumstances under which the file coordination machinery deadlocks.

WatchKit Data Sharing: Beware of the NSFileCoordinator and NSFilePresenter

Introducing MMWormwhole

ddeville / LLBSDMessaging: Interprocess communication on iOS with Berkeley sockets

Interprocess communication on iOS with Mach Messages

File Coordination Fixed: “In iOS 8.2 or higher, the obvious approach should now be safe.” as noted above.

Hakawai And Away

This is well worth taking a look at if you’re outgrowing UITextView’s functionality, LinkedIn is the latest company to kick out some awesome source to the community:

Introducing Hakawai – a powerful, mentions-enabled text view for iOS

Text Transformers

Hakawai provides block-based APIs for working with the contents of a text view. Text transformers are methods which take in special blocks. These blocks always take as an argument an attributed string (representing the initial state of the text), and return another attributed string (representing the final state of the text). Hakawai also supports attribute transformers, which work similarly…

Abstraction Layer

The experimental Abstraction Layer feature is a way to provide text view users with a higher-level change notification API than currently offered by the built-in UITextViewDelegate. There are five main types of notifications, each with associated data…

Extras

Hakawai comes with a host of extras, including (but not limited to):

  • An API for easily adding and removing accessory views from the text view
  • An API for temporarily locking the focus of the text view to the top or bottom of the text view
  • An API for rejecting autocorrect suggestions, and for working with the text view’s autocorrection, auto-capitalization, and spell checking state
  • A convenience API for working with characters and words at a given location
  • A custom text container and layout manager
  • Support for custom text formatting through custom attributes, including a pre-built attribute showcased in the mentions plug-in

Plug-ins

Hakawai supports plug-ins, which are code modules that can be selectively activated and deactivated at run-time to provide the text view with additional functionality…

Mentions

Mentions is a plug-in for creating ‘mentions’, annotations in a text view which might correspond to names of individuals or entities…

OK, that’s some serious UITextView enhancement. Check it out on github!

(And while you’re in the LinkedIn neighbourhood over there, background fetch scheduling library Selene is worth a gander as well.)

h/t: ManiacDev!

UPDATES:

raulriera / TextFieldEffects: “Custom UITextFields effects inspired by Codrops, built using Swift”

Stylish Setup: KZBootstrap And Fabric

We’ve scattered here and there various references to goodies that make managing your Xcode project easier and/or more reliable, but here’s a particularly sweet-looking collection of most all the best bits we’ve noted plus some new clevernesses:

krzysztofzablocki / KZBootstrap: “iOS project bootstrap aimed at high quality coding.”

Each configuration can be put side by side on same device, and you can clearly distingiush each build. Easier to find issues across different version and branches…

Automatically generate macro for current developer, that way a team can have different code paths while they are working on features, or different logging levels. Without git changes.…

Often when working with big clients, you need to have multiple environments for Staging / Production / QA etc. They usually differ in some kind of configuration … Environments can be changed without reinstalling application, even while it’s running…

assertions when UIKit is layouted/displayed on background thread, so you can fix your code…

Let’s put it this way, even if you’re not particularly interested in adopting all the goodies here wholesale, it’s a useful exercise to go through all the various capabilities and understand them for when they or something along their lines might prove useful. As well as the various source references:

And while we’re on the subject of setting up new projects, if you haven’t looked at Twitter Fabric yet we’d recommend that’s a good thing to do; as Crashlytics is the only third party service we regard as an absolute necessity for any project at the moment, and if the other services Fabric provides are as competently executed and easy to manage as Crashlytics is, well we for one welcome our new Twitter overlords!

UPDATES:

Speeding Up Custom Script Phases

futurice / ios-good-practices: “Good ideas for iOS development, by Futurice developers.”

indragiek / swiftrsrc “generates Swift code for accessing elements of asset catalogs, storyboards, and color lists in order to avoid the error-prone practice of hardcoding strings into your code. It is heavily inspired by Square’s objc-codegenutils, which you should definitely look into if you’re working on an Objective-C project.”

mac-cain13 / R.swift: “Tool to get strong typed, autocompleted resources like images and segues in your Swift project.”

SwiftGen 4.2 and other news

Natalie – Storyboard Code Generator

a convenient way to access child controllers inserted into Storyboard container views

13 Xcode Tips That Will Help You Conquer Xcode; Spicing Up Xcode; Xcode 6 Tips: Vector Images, Code Snippets and Many More

Extend Xcode with Text Services

Tool: Xcode Plugin Adding An Action Bar For Nearly Every Built-In Xcode Action And More

Xcode Plugin Listing – Quality Xcode Plugins

The Unofficial Guide to xcconfig Files

How To Recover Disk Space from Xcode

Core Motion Slickness

The always-invaluable NSHipster has some particularly nifty trickiness in an article on Core Motion:

CMDevice​Motion

Let’s say we want to give the splash page of our app a fun effect, with the background image staying level no matter how the phone is tilted … Using the gyroscope, Core Motion separates user movement from gravitational acceleration and presents each as its own property of the CMDeviceMotionData instance that we receive in our handler…

We can also use the other, non-gravity portion of this composited gyro/acceleration data to add new methods of interaction. In this case, let’s use the userAcceleration property of CMDeviceMotionData to navigate backward whenever a user taps the left side of her device against her hand…

Lastly, let’s try using the device’s attitude to enable a new interaction for a flash-card app, designed to be used by two study buddies. Instead of manually switching between the prompt and the answer, we’ll automatically switch the view as the device turns around, so the quizzer sees the answer while the person being quizzed only sees the prompt…

Read it all!

Resource Management: xcres

Well, this is the handy-dandiest resource helper we’ve seen in a while:

mrackwitz/xcres: xcres searches your Xcode project for resources

xcres searches your Xcode project for resources and generates an index as struct constants. So you will never have to reference a resource, without knowing already at compile time if it exists or not.

It includes loose images, .bundles, asset catalogs (.xcasset) and even .strings in the index.

It gives you code autocompletion for resources and localized string keys, without the need of an Xcode plugin.

Especially if your app is a bit more complex, this will greatly improve your workflow. It ensures a better quality and gives you more safety. You will see directly when a resource is missing, when you renamed it, or you moved it around.

Furthermore it won’t even bother you for trivial name changes like change capitalization or converting name scheme from train-case or snake_case to camelCase and vice versa.

It will warn you in Xcode on build, if certain resources or string keys can’t be references, because their name contain invalid chars, duplicates in the camelCase variant with another key, or would be equal to a protected compiler keyword…

We tend to keep our resource references pretty much in order by reflex when writing them actually, but looks like this might make that more streamlined. And looks like it would be downright invaluable the next time we’re handed some mess to make sense of written by someone who regarded the concept of ‘maintainability’ with fear and loathing apparently…

h/t: CocoaControls!

UPDATES:

Working with Localization in iOS 8 and Xcode 6 describes new string functionality

SpriteBuilder 1.3

Just in case you haven’t been keeping track of developments over in the Cocos2D-Swift (née cocos2d-iphone) world, you might want to take a look at how SpriteBuilder is continuing to shape up right nicely into a — nay, the — friendly cross-platform development environment:

SpriteBuilder 1.3 Beta

In this beta, you’ll get early access to exciting new features we’re working on for the 1.3 full release, including:

  • The all-new Cocos2D Metal renderer for iOS 8 (and compatible devices)
  • CCEffects UI – add and edit amazing effects in SpriteBuilder with a few clicks!
  • Packages in Cocos2D – load groups of resources dynamically in your game!
  • An improved OpenGL renderer with multithreading option
  • Other iOS 8 optimizations and bug fixes

And, last but not least… the SpriteBuilder Android Plugin, now in public beta!

The what?

The SpriteBuilder Android Plugin extends the Cocos2D game-building power of SpriteBuilder to both iOS and Android. The SpriteBuilder Android Plugin uses clang to cross-compile Objective-C to native ARM and x86 machine code – no virtual machines, emulators, or Java translation. Your app will run faster than a Java-equivalent Android application. Additionally, since you have full access to every iOS and Android API, you maintain complete control over how your application is built. The SpriteBuilder Android Plugin allows you to expand your game’s audience while still using the Xcode environment you are familiar with…

Last few months we’ve been picking away at getting an old school cocos2d game with heavy UIKit overlays up to speed with the apportable library. Our conclusion was that why yes once upgraded to Cocos2D-Swift 3.x the Cocos2D bits went quite impressively smoothly; the UIKit stuff … well, mostly there. With just enough not in that mostly to cut the experience down somewhat from unqualified success. Looks like our experiences there are not terribly unusual, as it seems like Apportable is doubling down on what they do well here and scaling back on the everything to everybody idea. Best of luck to ‘em!