Playgrounds for Objective-C

You need to watch this video

Playgrounds are awesome, Apple has made amazing job with Xcode 6 and Playgrounds were the icing on the cake.

They have multitude of use cases, eg.

prototype custom algorithms
design custom UI
learn the language or explore different API

But since most of us still need to write Objective-C I give you

Objective-C Playgrounds

Features:

Faster than Swift playgrounds (a lot)
Extra controls for tweaking:
Adjustable values
Auto-animated values
Buttons
IDE agnostic, once you run it, you can modify the code even from vim.
Full iOS simulator and access to all iOS features, so you can prototype production ready code.
Nice DSL for rapid prototyping
CocoaPods support, so you can add it to existing projects to experiment
Open source, anyone can contribute to make them better!

It’s just a start.

Technical details

First, let’s establish naming:

Timeline is a place where you have snapshots and controls.
Worksheet is a place where you can add views / controls and have interaction with them. You can use all the stuff you’d normally use with iOS like UIGestureRecognizers etc.
Tick counter - number of times the code changes have been loaded, multiply by the time it takes to compile + load your project and you see how much time you saved.

DSL’s

Timeline snapshots

KZPShow(obj)

CALayer
UIView
UIBezierPath
CGPathRef
CGImageRef
UIImage
NSString, with format or without
id

Implementing snapshotting for your custom classes

You can implement custom debug image:

- (UIImage*)kzp_debugImage;

If you have already implemented - (id)debugQuickLookObject that returns any of types supported by the KZPShow, you don’t need to do anything.

Controls

Button

KZPAction(@"Press me", ^{
// Magic code
})

Adjusters

KZPAdjustValue(scale, 0.5f, 1.0f) //- for floats
KZPAdjustValue(position, 0, 100) //- for integers

Also available as block callbacks KZPAdjust

Animations

Block animation callback, wrap the changes you want to be dynamic in them.

KZPAnimate(CGFloat from, CGFloat to, void (^block)(CGFloat));
KZPAnimate(void (^block)());

Auto-animated values, defines new variable and automatically animates them. AR -> AutoReverse

KZPAnimateValue(rotation, 0, 360)
KZPAnimateValueAR(scale, 0, 1)

Storing variables

Transient - Cleared with each code change

Instead of using instance variables / properties for KZPlayground class (you are fine to use them for normal classes that you create as part of playground), you should store playground specific variables that you need to reference between playground methods, eg. view you want to pan with UIPanGestureRecognizer inside transientObjects dictionary.

self.transientObjects[@"pannableView"] = view;

Persisted - Not cleared with recompilation

Implement setup method and use normal instance variables to store data you don't want to change on code change. eg. if you need to do some expensive operation.

Snapshots recorded during setup will persist in timeline.

- (void)setup
{
	self.data = [self fetchBigDataSet];
}

Installation and setup

KZPlayground is distributed as a CocoaPod: pod KZPlayground so you can either add it to your existing project or clone this repository and play with it.

Remember to not add playgrounds in production builds (easy with new cocoapods configuration scoping).

Once you have pod installed, you need to create your playground, it’s simple:

Subclass KZPPlayground
Implement run method
Conform to KZPActivePlayground protocol

You can have many playgrounds in one project, but only one should be marked as KZPActivePlayground. It will be automatically loaded.

present [KZPPlaygroundViewController playgroundViewController]

To apply your changes you have 2 approaches:

Xcode/Appcode you can use cmd/ctrl + x (done via dyci plugin) while you are modifying your code.
(My Preferrence) Automatic on file save (IDE agnostic) using kicker gem in terminal: (N.B. you need to have the kicker gem installed, see below)

kicker -sql 0.016 FOLDER_WITH_SOURCE_FILES

in case of Example project you'd call kicker from inside the project root folder (one containing Example and Pod)

kicker -sql 0.016 Example

This will react to all changes in .m files and reload your playground.

Only once

KZPlayground is powered by Dyci code injection tool, you only need to install it once on your machine (You’ll need to reinstall it on Xcode updates):

git clone https://github.com/DyCI/dyci-main.git
cd dyci-main/Install/
./install.sh

In order to use the kicker gem, you need to install it as follows:

(sudo) gem install kicker

Roadmap & Contributing

Recompilation of Xib
Recompilation of Storyboards
Integrate graph displays.
Resizable timeline/worksheet splitter.
Nicer visualisations for Arrays && Dictionaries.

Pull-requests and ideas for features are welcomed and encouraged.

It took me around 12h to get from idea to release so the code is likely to change before 1.0 release.

If you'd like to get specific features I'm available for iOS consulting.

License

KZPlayground is available under the modified MIT license. See the LICENSE file for more info.

Author

Krzysztof Zablocki, krzysztof.zablocki@pixle.pl

Follow me on twitter.

Check-out my blog or GitHub profile for more cool stuff.

Attribution

SceneKit example code has been taken from David Ronnqvist upcoming SceneKit book, recommended.

jasonzeng/KZPlayground