Cocoa Manifest

The Paradigms of Swift

2014年06月12日T23:54:00-07:00

Rob Napier on why Swift is not a functional language:

Swift is a multi-paradigm, but it’s not OOP/functional. It’s OOP/generic. Generic programming is primarily concerned with general purpose algorithms that can be applied to arbitrary types. It has some similarities with functional programming, and there are certainly languages that are both functional and generic, but generic programming doesn’t care if the algorithms are functions (things that take and return immutable values) or processes (things that mutate state).

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New O'Reilly Videos For iOS (with Yours Truly)

2014年06月08日T22:25:00-07:00

If you’ve ever wanted to peek over the shoulders of Josh Smith and me to watch how we build iOS applications, check out these brand new videos published by O’Reilly. We cover a range of stuff from the paper prototyping phase to how we approach building transitional animations, debugging, testing, and more.

We are quite proud of how these videos turned out. We had a chance to be among the first batch of O’Reilly’s new video content initiative. Josh has even gone on by himself to do a video on Core Data and security (should be out soon). It’s been an honor and a lot of fun to work with the O’Reilly team. They have a professional video crew that did all the dirty work with lighting, framing, and editing. We just brought the content.

If you’re interested in doing videos of your own content with O’Reilly then get in touch with Amy Jollymore. They are looking for new authors.

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Unit Testing with Swift

2014年06月06日T10:31:00-07:00

Brad Grzesiak wrote up some of his findings while trying to unit test Swift code.

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Where The Metal API Could Be Headed

2014年06月03日T22:27:00-07:00

For those who (like me) were curious to know more about the reasoning beind the new Metal API Apple announced at WWDC 2014, Ryan Smith at AnandTech describes why the graphics industry wants to strip away the higher layers like OpenGL and DirectX for better performance. He also speculates about use beyond graphics:

The low-level nature of Metal on the other hand means that it’s a good (or at least better) fit for GPU computing, as the lack of abstraction for graphics makes it more capable of handling the workflows and data types of compute tasks. This is one area in particular where the Metal shader language being based on a subset of C++11 is a benefit to Apple, as it provides a solid foundation for writing compute kernels.

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✦ Announcing KeyGrip: the Pasteboard Presentation Tool

2014年04月30日T16:33:00-07:00

Josh Smith and I have been busy building a tool to help us tell a story while live coding in our presentations and workshops. We’ve decided to open source it and we’re ready to share it with you.

Behold: KeyGrip.

A while back Apple wrote a Mac app called Demo Monkey that gave you a list of things you could click on to put them on the pasteboard. It made presenting code a little bit easier since you could break up what you wanted to show into chunks, weave it into a narrative, and paste as you go to demonstrate.

But that required having a window visible on your Mac with a list of clips. And if you’re like me, you still needed script notes somewhere near by to stay on track and remember what clip goes where in the flow.

That’s why we wrote KeyGrip. After iterating on a few different ideas, we settled on a Mac server and a Universal iOS client. Run the client on an iPad Mini and it shows your presenter notes interspersed with code snippets—all generated from a Markdown file. If you tap on any of the code snippets, it instantly shows up on your Mac’s pasteboard.

The Mac and iOS apps communicate seamlessly over Bonjour. All you have to do is make sure they have the same string identifier so they can find each other. The Mac server also live pushes changes to the iOS client while you work on the Markdown script. You can get into a slick editing workflow where you adjust your notes and try out your code examples.

Yeah, I’m biased. But I gotta say...this thing is like magic.

You can download a binary of the Mac server right from the README. You can download the source and build the iOS app to install it on your favorite device. Enjoy!

Oh, and special thanks to Derek Briggs for the icon. He’s got plans to help us polish up the interface a bit over time, too. :)

✦ UI Screen Shooter - Now Simpler and More Robust Since Xcode 5.1

2014年03月14日T15:03:00-07:00

The UI Screen Shooter scripts have been updated for Xcode 5.1! I’m quite pleased with the results. The instruments command line tool now lets us specify the simulator device directly from the command line. I’ve cleaned up the scripts and they are much easier to follow. Kudos to Apple on this! And thanks to Christoph Koehler’s issue that brought all this to my attention.

If you’d like more details on what changed, read on.

The Old Way of Hacking Things

You no longer have to force Xcode to pick the iPhone architecture with the TARGETED_DEVICE_FAMILY configuration parameter. Previously, the instruments command line tool would not let you pick whether you wanted to run on the iPad or iPhone simulators. If an app was marked as universal, Instruments would always launch the app in the iPad simulator. The hack to get around that was to set the TARGETED_DEVICE_FAMILY to 1 which would force Xcode to build the app as iPhone only. Instruments would then oblige and only launch the iPhone simulator.

In order to get screenshots on both iPad and iPhone, you had to build twice with different TARGETED_DEVICE_FAMILY settings. It was a real pain, but it worked.

You also no longer have to muck with the simulator preference files to force the simulator to launch in a specific language. Previously, I hacked together a shell script that used PlistBuddy to alter the preference files, forcing the simulator to think only a specific language and locale was available. But thanks to a post by Ole Begemann on NSUserDefaults, I realized that I can force the simulator to pick a locale by just passing special command line parameters.

And that’s not all! You also no longer need to force the simulator to a specific device model with AppleScript! Previously (you can see a theme here), I used an AppleScript that launched the simulator and picked the proper device type from the Hardware menu. When Instruments next launched, it would use the previous simulator setting. Again, it worked but it was a horrible hack.

Update: Brad Grzesiak just pointed out to me that there’s no longer the need for my pty/tty hack in the unix_instruments wrapper since the Instruments command line tool no longer buffers it’s output when piped. We still need the wrapper script, though, because Instruments doesn’t return a non-zero status code on JavaScript failure, but hey, I’ll take every opportunity I can get to remove my workaround code.

The New, Glorious Way

All that changed in Xcode 5.1 because Instruments now supports specifying the simulator hardware type and iOS version all from the command line! To find out what options you currently have you on your machine, just type the following:

instruments -w help

And then you’ll see something like this:

iPhone Retina (3.5-inch) - Simulator - iOS 7.1
iPhone Retina (4-inch) - Simulator - iOS 7.1
iPhone Retina (4-inch 64-bit) - Simulator - iOS 7.1
iPad Retina - Simulator - iOS 7.1
iPad Retina (64-bit) - Simulator - iOS 7.1
...

Finally! It doesn’t matter what you put after the -w flag. You just need to pass something invalid and instruments gives you the valid options. Pass one of these strings in like so to use it:

instruments -w "iPad Retina - Simulator - iOS 7.1" ...

Note that you need the quotation marks because of the spaces in the full name of the simulator hardware type and version. Also, the -w flag must come at the start of the command line, before any other flags. Otherwise you get strange errors.

Check out the full screen shooter repository for more details. Use this as the basis to write your own screen shooting scripts. Enjoy!

Our Sprite Kit Book Now In Beta

2014年03月05日T10:47:00-08:00

Josh Smith and I have been working on a Sprite Kit book with the Pragmatic Programmers for the past few months. It’s now released in beta!

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Yes, that Brent Simmons

2014年02月27日T08:08:00-08:00

I’m quite enjoying Brent Simmons’ series of posts on his conversion back to Core Data from raw SQLite in the Vesper app. Yes, that Brent Simmons. In each post he states his latest concerns, asks questions, makes decisions, and follows up as he gets more information. It’s generated some heated discussions, yet he reacts graciously. Watching his design decisions change as he gets real time feedback is a treat. It’s like a case study for productive dialog.

Update: And thus far, he’s decided to abandon Core Data and return to raw SQLite with FMDB.

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NSUserDefaults - Not Just For Persistent Settings

2014年02月26日T10:47:00-08:00

Ole Begemann just wrote a nice article on NSUserDefaults. It’s a good overview for newcomers to the platform, but it also highlighted a feature that I hadn’t considered before—domains.

Different configuration data can come from, or be stored, in different domains. What surprised me most was the NSArgumentDomain. It’s a volitile storage space (won’t be persisted across app runs) and is populated at app launch from command line parameters. Remember the strange command flag syntax to turn on Core Data’s SQLite debug logs? It sets the values in the NSArgumentDomain of the app’s NSUserDefaults.

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Don't Write Off Tinkering In The Garage

2014年02月25日T09:23:00-08:00

Andy Arvanitis, of eero language fame, is at it again and experimenting with Idris, a Haskell like language with a simple interface to C. Which, of course, means he’s experimenting with bridges to Objective-C classes.

Idris fascinates me because it not only has a flexible syntax, but you can define your own syntax rules on the fly¹. Andy shows off how he builds the same bracket and parameter list syntax you’re familiar with in Objective-C. It’s like programming language putty.

I love this kind of stuff. I know, I know, this adds to the complaint fodder about the creaking husk of Objective-C. I applaud work like what Andy is doing precisely because it charges our imagination with what’s possible—borrowing useful solutions in other arenas to experiment at the intersection of Objective-C/Cocoa’s history and today. I’m all for what happens when someone hermits up, thinks hard, and designs a language with specific goals. But, don’t write off the tinkering in the garage.

And you thought Ruby’s metaprogramming possibilities were frightening!↩

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Apple's Secure Coding Guide

2014年02月24日T11:12:00-08:00

Apple’s Secure Coding Guide. Linked non-ironically.

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Security Is Code Formatting

2014年02月24日T11:02:00-08:00

What a weekend. Apple released iOS 7.0.6 to plug a hole that let’s an attacker "capture or modify data in sessions protected by SSL/TLS". Vague and ominous.

Then Adam Langley wrote up an excellent summary of the problem after code spelunking through the open source bits of iOS and OS X. W. T. F.

It’s all because of a goto statement that skips proper TLS verification under some circumstances. It was missed because of indentation that made it look like it was part of the if statement above. But because the if statement lacked curly braces, only the immediately following statement was covered by the conditional. The second goto always runs and skips the rest of the critical verification code. If an attacker knows how to cause this sequence of events, they have free reign with a man-in-the-middle attack.

<hindsight type="shameless" scope="20/20">
Check brace-less conditionals and formatting, please. And write tests for security code wherever possible.
</hindsight>

By the way, Golang’s code formatter would have enforced curly braces for these if statements and reformatted indentation to expose the lone goto automatically. Compiler enforced formatting rules for the win, eh?

For even more details, read Dave Farber’s write up of the situation.

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DTrace - Lightning Stolen From The Unix Gods For Use By Mere Mortals

2014年02月12日T11:07:00-08:00

After linking to the enjoyable read on strace by Chad Fowler, Mark Dalrymple enticed me to point out DTrace, which you might have heard of as the magic engine running under Apple’s Instruments monitoring and debugging tool. Personally, I’ve spent more time in Instruments than down in the bowels of DTrace, but I’ve bookmarked Mark’s posts as my starting place for when I need it.

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strace - Tool of The Unix Gods

2014年02月10日T10:10:00-08:00

Chad Fowler wrote up his experiences using strace to debug Lotus Domino problems back in the day. It’s a great story and a nice introduction to a useful tool for anyone using a language bolted on top of C and the Unix subsystems—like, say, Objective-C programmers!

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Solving The Huge View Controller Problem

2014年02月05日T11:49:00-08:00

Brad Grzesiak wrote a thoughtful piece on following the single responsibility principle when building view controllers in storyboards. His take challenged me since I had always thought the single responsibility principle was just a good guideline for making sure a class doesn’t do too much right now. But, as Brad points out:

By focusing on why the class might have to be changed, the Single Responsibility Principle allows us to think of how we interact with the code in the present instead of requiring us to project our minds onto the software’s future running environment. This, I believe, is an important, and freeing, distinction.

In other words, separating out the responsibilities clarifies where we need to look when requirements change. And the requirements always change. Software shares much in common with living organisms that must adapt to their environment. That adaptation is quite messy. The organism could get sick or sprout cancerous growths. It’s quite different from the process to build a finished structure, like a bridge, that only changes as it degrades according to the properties of the materials it was built with.

Brad demonstrates how he tries to minimize those cancerous growths in his software. It’s good to see more examples of breaking apart the responsibilities of a view controller into collaborating objects that all live together in a storyboard scene.

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Cocoa Manifest

The Paradigms of Swift

New O'Reilly Videos For iOS (with Yours Truly)

Unit Testing with Swift

Where The Metal API Could Be Headed

✦ Announcing KeyGrip: the Pasteboard Presentation Tool

✦ UI Screen Shooter - Now Simpler and More Robust Since Xcode 5.1

The Old Way of Hacking Things

The New, Glorious Way

Our Sprite Kit Book Now In Beta

Yes, *that* Brent Simmons

NSUserDefaults - Not Just For Persistent Settings

Don't Write Off Tinkering In The Garage

Apple's Secure Coding Guide

Security Is Code Formatting

DTrace - Lightning Stolen From The Unix Gods For Use By Mere Mortals

strace - Tool of The Unix Gods

Solving The Huge View Controller Problem

Yes, that Brent Simmons