Archive for the ‘Xcode’ Category

Adding syntax highlighting and source file support for TypeScript to Xcode

Thanks to a prior solution created by Steve Troughton-Smith for Lua, I was able to hack together an Xcode Plug-In (yeah, those still exist) for 10.1.

TypeScript repo is here at github.

To install, quit Xcode. Run to add the xclangspec and ideplugin info to your ~/Library/Developer/Xcode folders. Then launch Xcode, agree to allow the plug-in to run, and then add your ts files.

The file inspector will still say they’re MPEG-2 Transport Stream files but you’ll be able to see the text, the text will be formatted, and you can use Xcode to search for content within the files. Let me know if it works for you.

The xcplugin and the xclangspec were easy to put together, because I just riffed on JavaScript’s syntax. Other languages will take a bit more work because you have to set up a list of keywords and their characters and syntax coloring rules, which may or may not lend themselves to easy lexer support.

Xcode Symbology Challenge! Find examples, identify icons, gain fame and glory

You know those little icons in the Xcode developer docs? Like the 4 squares for frameworks or the M for method? How many can you find and give examples for? Also how many can you identify off the top of your head? Do you know what each of these are and what they represent?

What follows is an exhaustive list sourced from an internal Xcode framework. For each of the following, your challenge is to describe what the icon looks like and offer an example that uses the icon. For example “T” is a type alias. You can find one by following UIKit > Drawing > UIGraphicsPDFRenderer.DrawingActions or searching for DrawingActions.

  • article
  • category
  • class
  • class extension
  • constant
  • endpoint
  • enum
  • extension
  • field
  • framework
  • function
  • group
  • local_variable
  • macro
  • method
  • object
  • operator
  • property
  • protocol
  • sample code
  • struct
  • subscript
  • typedef
  • union
  • variable

Have fun and drop a comment with a link to your finds. Please don’t put answers here directly as that may spoil the challenge for others.

Prototyping CoreGraphics in the Playground

No matter how flaky, I love using playgrounds to prototype Core Graphics, SpriteKit, and many other see-as-you-go technologies. They’re fantastic for building out specific custom content with a bare minimum of coding investment. You get a lot of win for very little time.

I was helping someone out the other day, explaining the strokeEnd keypath (versus the path keypath) and building a playground showed it off to perfection.

Admittedly, it helps to have quick helper code on-hand for quick starts. I have playground-specific setup code, handing me a view controller (called vc) and a centered view, ready to start demo-ing in this one.

I also have a couple of pages of code (like the layer(path:) constructor, the animateStrokemethods, and the schedule() utility off page, in the support module. They’re all highly reusable. It’s a pity in-playground debugging is so dreadful. It would be an ideal module-building tool if not for that: build and explore (and ideally build tests) in a single place, without having to be in a fixed workspace lacking the exploration feature. Adding “convert this exploration into a test” would be icing on top.

I’m disappointed that playground-specific visualizations built for teaching and demos don’t transfer to the debugger for real-world production support. I don’t see any reason why a CGPoint instance should get a pretty graphic representation but a CGAffineTransform, for which I have quite a full presentation, does not.

I can use custom mirroring to produce valuable output for dump, and therefore for printing objects in the debugger but not for debug quicklooks. Plus as far as I can tell the custom NSObject-only quicklooks haven’t been updated in years and there’s no hint of extending this to structs and enums.

By the way, what’s the deal with all the API audits? How long are these going to go on? If you thought updating the app delegate was a minor nuisance, you haven’t seen what’s happened to all the constants and Core Graphics APIs. This update is huge and disruptive…

Converting projects by hand to Swift 4.2

If Xcode is acting up for you the way it is for me, you may want to step back from automated migration and just do it by hand. I spent far too much time this morning trying to get Xcode to finish migrating for what were extremely trivial changes.

If you’re going by hand, make sure to change your “didFinishLaunching” launch options (in your App delegate) from [UIApplicationLaunchOptionsKey: Any] to use UIApplication.LaunchOptionsKey. (Notice the period in the name.)

To set the compiler from Swift 4 to Swift 4.2, open Target > Build Settings. Navigate to Swift Language Version and use the pop-up to select the proper compiler:

For some projects (especially small sample code) this alone may be sufficient to get you back and working.

Simulators gone bad

Recently, some of my simulators launched and loaded just fine. Others simply went black. It didn’t seem to matter which firmware I was simulating. Some devices were just happier than others.

Naturally, I turned to the system console, which provides device-by-device logs, but I couldn’t really find anything.

I tried restarting and rebooting the sims. I tried resetting the core simulator service. I tried a lot of things. (No actual chickens were harmed.) Finally, I stumbled across a Apple Dev Forum thread about issues with the beta system. The advice offered in-thread was this:

  • Quit the simulator. (I also killed because reasons.)
  • Run xcrun simctl erase all
  • Set a framebuffer renderer hint: defaults write FramebufferRendererHint 3

It worked.

Yay! \o/

From the thread, apparently hints 1 and 2 do not work but 3 does. An Apple Engineer noted that, “hint 0 is auto (currently prefering Metal and then falling back to OpenGL if unavailable). Hint 1 prefers Metal and hint 3 prefers OpenGL. Hint 2 used to mean OpenCL, but we dropped OpenCL support.”

Upshot is that I lost many hours but I seem to have a working solution for dealing with a common problem. I hope this write-up helps you if you encounter the same issues.

Update: Guru Russ Bishop recommends against using this long term. He writes

If you (as I) have deadlines, and cannot wait for this problem to be fixed, this fix will get you back to work. Russ reminds me, though, “Use it temporarily only if you have this problem, and don’t forget to delete the pref in the future”

Auto Layout, Playgrounds, and Xcode

Today, someone asked what the easiest way was to center a view (specifically a UIImageView) inside a parent view with minimum offsets from the top and sides.

Because you’re working with image views, it’s important that you first set the content mode. For insets, it’s almost always best to go with a “fitting” aspect-scale, which preserves the entire picture even if it has to pillarbox or letterbox. (Pillarboxing adds extra spacing to each side for tall images; letterboxing adds the top and bottom for wide ones.)

// set content mode
imageView.contentMode = .scaleAspectFit

Make sure your view can squish its content by lowering its compression resistance:

[UILayoutConstraintAxis.horizontal, .vertical].forEach {
            UILayoutPriority(rawValue: 100), for: $0)

You must preserve your image’s aspect ratio. Calculate your target ratio by dividing its width by its height:

let size = imageView.image?.size ?? CGSize()
let aspectRatio = size.width / size.height

Add strong constraints that preserve the aspect, and make the view smaller than its parent using inset values you supply:

let insets = CGSize(width: 20.0, height: 32.0)

let constraints = ([
    // Preserve image aspect
        .constraint(equalTo: imageView.heightAnchor, multiplier: aspectRatio),
    // Make view smaller than parent
        .constraint(lessThanOrEqualTo: parentView.widthAnchor,
                    constant: -insets.width * 2),
        .constraint(lessThanOrEqualTo: parentView.heightAnchor,
                    constant: -insets.height * 2),

    // Center in parent
        .constraint(equalTo: parentView.centerXAnchor),
        .constraint(equalTo: parentView.centerYAnchor),

If you want to be super cautious, keep the aspect and two center constraints at 1000 and bring the width and height ones down to 999. You can install the constraints as you create them but I prefer to break that part out so I can tweak the priorities for each constraint group:

constraints.forEach {
    $0.priority = UILayoutPriority(rawValue: 1000)
    $0.isActive = true

I always mess up with the signs (positive or negative) of the constants. It helps to test these out in a playground rather than going by memory because the signs aren’t always intuitive. Even better, write routines that automates your Auto Layout tasks because if you debug once (and add proper tests), you never have to think about it again.

Mac playgrounds are inherently superior to iOS ones as they don’t run a simulator and are faster and more responsive. That is to say, you don’t have to quit and relaunch Xcode quite so often. If you are debugging iOS layouts though, and your playground hangs when starting the simulator or running your code, learn to quit, kill the core simulator service, and relaunch Xcode. It will save you a lot of time.

I have a one liner in my utilities to deal with the service:

% cat ~/bin/simfix
killall -9 -v

Most of the time a single quit, simfix, and launch will get things moving again with recalcitrant iOS playgrounds. Be aware that malformed format strings and other auto layout issues won’t produce especially helpful feedback, especially compared to the runtime output of compiled projects. If you know what you’re doing, you can set up a simple layout testbed in playgrounds with less overhead and time than, for example, a one view project but at a cost.

Stick to projects, and avoid playgrounds, when testing even mildly complex code-based layouts. You cannot, at this time (at least as far as I know), control which simulator will be used in the playground so it’s not great for checks on a multitude of simulator geometries. The tl;dr is that playgrounds work for general layout routines. Prefer compiled projects for specific tasks.

Beta 3 Playground Workarounds

Adding Resources and Sources folders to Playgrounds

Until they’re fixed, you may have to add them by hand.

  1. Right-click/control-click.
  2. Show package contents
  3. You can add new Resources and Sources files at the top level
  4. Alternatively, navigate down to individual pages (which are finally in Beta 3!) by showing their package contents and add them there

Fortunately under Beta 3 you don’t have to manually add pages, as the new page functionality is finally back.

Creating New Playgrounds

They’re no longer listed in the File > New dialog. Instead choose File > New > Playground (Command-Shift-Option-N) or open “Welcome to Xcode” (Command-Shift-1) and click “Get started with a playground”.

Most of the obvious alternatives (like Command-Control-N, which creates new workspaces) are already taken, but if you don’t mind using the menu for that, I think it’s a nicer key binding for “New Playground”. If you want to mess with this open prefs (Command-comma), type playgrounds into the search field, and edit the key binding for “New > Playground”

Don’t forget that new playground page is “Command-Option-N”.