Under the Bridge

So you catch the new Swift 1.2 seed yet? If not, looks like we could call this the Daft Punk release:

• Harder — “compiler crashes have been fixed”, “fewer SourceKit warnings” …
• Better — “Source files that haven’t changed will no longer be re-compiled by default…”
• Faster — “Debug builds produce binaries that run considerably faster, and new optimizations…”
• Stronger — “the language has been further refined to ensure safe, predictable behavior. We also continue to improve the interaction between Swift and Objective-C…”

Time to get on the latest rewrite round! Here’s a selection of good discussions of those “has been further refined” details:

NSHipster’s Swift 1.2

RayWenderlich.com’s What’s New in Swift 1.2

SwiftDoc.org’s Major content update for Swift 1.2

Let’s Talk About Sets, Baby!; Swift Set Type in Swift 1.2

Changes to the Swift Standard Library in 1.2 beta 1

Swift 1.2 Performance: Pretty Much Fine; Performance Case Study on Swift 1.1, Swift 1.2, and Objective-C; Swift Performance in Xcode 6.3 Beta

Also, we’d like to draw your attention to a couple so far generally overlooked points that have shown up on boards and mailing lists. First off, the souped up if let

The “if let” construct has been expanded to allow testing multiple optionals and guarding conditions in a single if (or while) statement using syntax similar to generic constraints:

if let a = foo(), b = bar() where a < b, let c = baz() {}

This allows you to test multiple optionals and include intervening boolean conditions, without introducing undesirable nesting (i.e., to avoid the “pyramid of doom”). (19382942)

is actually more souped up than those notes make fully clear:

• can be an arbitrary number of let + where clauses in a single statement
• can also be used with ‘if var’ should you wish to mutate values in the conditions
• can also use a full multiple clause statement in a while loop!

That should be quite enough conditional flow expressivity to quiet all the grumbling on that front.

Next, if you’re chomping at the bit to add the new return value contract annotations to your legacy Objective-C headers, “nullability” is the so far undocumented clang feature for that, so here is a currently-submittable way to add that to production code, from Jens Alfke on the Xcode list:

So the magic invocation I’m putting in my header files (after the #includes) is:

#if __has_feature(nullability) // Xcode 6.3+
#pragma clang assume_nonnull begin
#else
#define nullable
#define __nullable
#endif

… interface declarations go here…

#if __has_feature(nullability)
#pragma clang assume_nonnull end
#endif

In property declarations you’ll need to make “nullable” the last meta-attribute, otherwise you’ll get syntax errors in earlier versions of Xcode; so for example “(readonly, nonatomic, nullable)” works but “(readonly, nullable, nonatomic)” is a syntax error because in Xcode 6.1 the parser will see two adjacent commas.

[This is working well, but in converting my interfaces I found a nasty compiler bug that I’m about to submit to Apple — if you declare multiple properties on a single line, adding the (nullable) attribute will cause the parser to lock up in an infinite loop:
@property (readonly, nullable) id a, b, c; // don’t do this!
I spent an hour or so with my MBP’s fan running full speed before figuring out which exact line triggered this.]

Lastly, one of the more subtle consequences of Swift 1.2 no-op cleanup is that you can no longer cleanly use ? as a postfix on an optional optional, as for instance when using map on an optional dictionary lookup:

let x:Int? = dict.map { $0["a"] }?

The Chris Lattner approved way to rewrite this pattern for 1.2 is

let x:Int? = dict.map { $0["a"] } ?? nil

to make it more clear to the reader exactly what the intention is here.

So we’re pretty chuffed with how this Swift thing is coming along; pretty much every undue pain point seems addressed to wide satisfaction around teh intertubes — so if you’ve been holding off on jumping in, NOW might be a very good time to get on that!

Here’s an interesting set of links from an HN discussion, should you be interested in making a roguelike of your own some day as All True Programmers Are:

Another cheap and very effective technique for procedural level and maze generation is to create a “walker” or series of walkers that start at some point, walk in a direction and then turn at random intervals, leaving a path of corridors and occasionally rooms in their wake. This is how Vlambeer’s Nuclear Throne generates its levels, and there’s a good article from Jan Willem Nijman, it’s developer, here…

If you’d like a more academic look into procedural 2d game generation, there’s a nice research paper here, that describes a method and talks about Spelunky a lot (the king of procedural 2d level generation, in my book)…

Additionally, Derek Yu open sourced the code to the original Spelunky, and Darius Kazemi created a great breakdown of its level generation techniques here, also with interactive examples…

The action roguelike genre, particularly the roguelike FPS, is a vital new area being explored by indie game developers. It reminds me of the way 2D platformers were mined, explored, and iterated upon starting around 7 or 8 years ago…

Cool stuff! At least to us old school types who still think ASCII Nethack is TEH BESTEST GAME EVAR!!!1!one!!!

UPDATES:

Rooms and Mazes: A Procedural Dungeon Generator

Building a Procedural Dungeon Generator In C#

In case you’re not on the AWS mailing list like apparently we got onto somehow, there’s a new version of the AWS mobile SDK out, and it looks like it might be worth some serious consideration for your cross platform back end needs:

The AWS Mobile SDK helps you build high quality mobile apps quickly and easily. It provides access to AWS Mobile services, mobile-optimized connectors to popular AWS data and storage services, and easy access to a broad array of other AWS services…

And what are these services? Quite a bit actually:

Amazon Cognito makes it easy to save user data, such as app preferences or game state, in the AWS Cloud without writing any backend code or managing any infrastructure. You can save data locally on users’ devices allowing your apps to work even when the devices are offline. With Amazon Cognito, you can focus on creating great app experiences instead of having to worry about building and managing a backend solution to handle identity management, network state, storage, and sync.

Amazon Mobile Analytics lets you easily collect, visualize, and understand app usage data at scale. Amazon Mobile Analytics is designed to provide aggregated data within 60 minutes of receiving events from an app so that you can act on the data more quickly. With Amazon Mobile Analytics, you get 100 million events per month for free.

Amazon Simple Notification Service (Amazon SNS) makes it simple and cost-effective to push notifications to Apple, Google, Fire OS, and Windows devices, as well as Android devices in China with Baidu Cloud Push. You can also use SNS to push notifications to internet connected smart devices, as well as other distributed services. You get 1 million notifications/month for free.

Amazon Simple Storage Service (S3) provides secure, durable, highly-scalable object storage. Amazon S3 is easy to use, with a simple web services interface to store and retrieve any amount of data from anywhere on the web, and the AWS Mobile SDK includes additional functionality to optimize access from a mobile device.

Amazon DynamoDB is a fast and flexible NoSQL database service for all applications that need consistent, single-digit millisecond latency at any scale. It is a fully managed database and supports both document and key-value data models. Its flexible data model and reliable performance make it a great fit for mobile applications.

Amazon Kinesis is a fully managed service for real-time processing of streaming data at massive scale. Amazon Kinesis can continuously capture and store terabytes of data per hour from hundreds of thousands of sources such as mobile app events and website clickstreams. You can also emit data from Amazon Kinesis to other big data services such as Amazon S3, Amazon Redshift, and Amazon Elastic Map Reduce (Amazon EMR).

Haven’t used any of this either v1 or v2 ourselves, but if you feel like trying it, there’s a 12-month free plan; sign up, check it out,

To get started, learn more at http://aws.amazon.com/mobile and download the iOS or Android SDK. Engage with the AWS developer community on the AWS Mobile forums or our Github Android|iOS repositories. To stay up-to-date, follow us on Twitter at @awsformobile.

and let us know how that went for you!

Here’s a handy little Swift library for adding a dab of style to your string rendering:

lvnyk / BezierString: Rendering NSAttributedStrings along arbitrary UIBezierPaths

Take your string and your path and generate a UIImage, draw into a CGContext, or use UIBezierLabel anywhere you’d use a common-or-garden UILabel. Cool beans!

And if you’re not overly familiar with UIBezierPaths, check out some of our other mentions of their care and feeding and applied niftiness:

Bézier Path Construction

Bezier Path Boolean Ops

Bezier PathMove

Core Animating Interfaces

Library: Capture a Signature

h/t: ManiacDev!

UPDATES:

How to curve CGMutablePath? — mayoff / path-warp: UIBezierPath+Rob_warp.h

Custom UIView Animations with Vector Graphics

Cubic Bezier Curves Under the Hood

Open Source iOS Library That Adds Caching To UIBezierPath For Increased Performance

Mastering the Bézier Curve in Sketch

jmenter / JAMSVGImage: “Display resolution independent SVGs in iOS.”; timrwood / SVGPath: “Parse SVG path strings into UIBezierPaths in Swift”; The Ultimate Guide to SVG; check out our old SVGKit notes