Closures make code clear and readable. You can write self-contained, small snipets of code instead of having the logic spread throughout your app, Cocoa is moving slowly to a block/closure approach but there are still a lot of Cocoa libraries (such as UIKit) that don't support Closures. ClosureKit hopes to facilitate this kind of programming by removing some of the annoying - and, in some cases, impeding - limits on coding with closures.

• iOS 7.0+
• Xcode 8.3+

CocoaPods is a dependency manager for Cocoa projects.

CocoaPods 0.36 adds supports for Swift and embedded frameworks. You can install it with the following command:

$ gem install cocoapods

To integrate ClosureKit into your Xcode project using CocoaPods, specify it in your Podfile:

source 'https://github.com/CocoaPods/Specs.git'
platform :ios, '8.0'
use_frameworks!

pod 'ClosureKit'

Then, run the following command:

$ pod install

Closure control event handling for UIControl

let button = UIButton.buttonWithType(.System) as! UIButton
button.addEventHandler(forControlEvents: .TouchUpInside) { button in
    println("Button touched!!! \(button)")
}

Closure functionality for UIGestureRecognizer.

let doubleTap = UITapGestureRecognizer { gesture, state in
    println("Double tap!")
}
doubleTap.numberOfTapsRequired = 2
self.addGestureRecognizer(doubleTap)

Closure support for UIWebView delegate.

let webView = UIWebView()
webView.shouldStartLoad = { webView, request, type in
    println("shouldStartLoad: \(request)")
    return true
}

webView.didStartLoad = { webView in
    println("didStartLoad: \(webView)")
}

webView.didFinishLoad = { webView in
    println("didFinishLoad \(webView)")
}

webView.didFinishWithError = { webView, error in
    println("didFinishWithError \(error)")
}

UIImagePickerController with closure callback(s).

let picker = UIImagePickerController()
picker.didCancel = { picker in
    println("DID CANCEL! \(picker)")
}
picker.didFinishPickingMedia = { picker, media in 
    println("Media: \(media[UIImagePickerControllerEditedImage])")
}
self.presentViewController(picker, animated: true, completion: nil)

Closure wrapper for key-value observation.

In Mac OS X Panther, Apple introduced an API called "key-value observing." It implements an observer pattern, where an object will notify observers of any changes in state. NSNotification is a rudimentary form of this design style; KVO, however, allows for the observation of any change in key-value state. The API for key-value observation, however, is flawed, ugly, and lengthy.

Like most of the other closure abilities in ClosureKit, observation saves and a bunch of code and a bunch of potential bugs.

WARNING: Observing using closures and cocoa observers are independant. Meaning that you shouldn't add a "traditional" observer and then remove it using this wrapper nor add a closure observer and remove it using Cocoa methods.

self.observeKeyPath("testing", options: .New | .Old) { newValue, oldValue in
    println("Property was: \(oldValue), now is: \(newValue)")
}

MFMailComposeViewController with closure callback.

Note that when setting a completion handler, you don't have the responsability to dismiss the view controller anymore.

let composeViewController = MFMailComposeViewController { viewController, result, type in println("Done") }
composerViewController.setSubject("Test")

MFMessageComposeViewController with closure callback.

Note that when setting a completion handler, you don't have the responsability to dismiss the view controller anymore.

let composeViewController = MFMessageComposeViewController { viewController, result in println("Done") }
composerViewController.body = "test sms"

Closure event initialization for UIBarButtonItem.

self.navigationItem.rightBarButtonItem = UIBarButtonItem(image: image, style: .Bordered) { btn in
    println("Button touched!!!!!! \(btn)")
}

CADisplayLink closures implementation.

CADisplayLink.runFor(5.0) { progress in
    println("Awesome \(progress * 100)%")
}

Closure implementation of CLLocationManager delegate.

Note that when using startUpdatingLocation(handler) you need to use the counterpart stopUpdatingLocationHandler or you'll leak memory.

Example:

let locationManager = CLLocationManager()
locationManager.starUpdatingLocation { location in
    println("Location: \(location)")
}
locationManager.stopUpdatingLocationHandler()

WARNING: You cannot use closures and set a delegate at the same time. Setting a delegate will prevent closures for being called and setting a closure will overwrite the delegate property.

Simple closure implementation on NSTimer scheduling.

NSTimer.scheduledTimerWithTimeInterval(1.0, repeats: false) { timer in
    println("Did something after 1s!")
}

WARNING: You cannot use closures and set a delegate at the same time. Setting a delegate will prevent closures for being called and setting a closure will overwrite the delegate property.

Martín Conte Mac Donell @fz