Swift Extensions: NSTimer

NSTimer.md

NSTimer is a great example of an over-verbose, outdated Objective-C API. To run a simple line of code after a delay, you need to write a lot of boilerplate crap.

How about this:

NSTimer.schedule(5.seconds) {
  println("Hello world!")
}

So much better. How about a timer that repeats every second? Swift supports optional parameters, so we could do repeat: true, but how about:

NSTimer.schedule(every: 1.second) {
  println("Hello world!")
}

Sweet. But what if you want to schedule the timer yourself? (e.g. for event tracking run loop mode)? Just cut the .schedule part out:

let timer = NSTimer(every: 1.second) { println("Hello world!") }

Want to use a separate method after all? No problem:

func printFoo() {
  println("Hello world!")
}

NSTimer.schedule(1.second, block: printFoo)

(after all, functions and methods are just named closures)

PS. I wrote something very similar in Objective-C before.

---

Previously in Swift Extensions:

• NSStoryboard

NSTimer.swift

import Foundation

private class NSTimerActor {
    var block: () -> ()
    
    init(block: () -> ()) {
        self.block = block
    }
    
    dynamic func fire() {
        block()
    }
}

extension NSTimer {
    convenience init(_ intervalFromNow: NSTimeInterval, block: () -> ()) {
        let actor = NSTimerActor(block: block)
        self.init(timeInterval: intervalFromNow, target: actor, selector: "fire", userInfo: nil, repeats: false)
    }
    
    convenience init(every interval: NSTimeInterval, block: () -> ()) {
        let actor = NSTimerActor(block: block)
        self.init(timeInterval: interval, target: actor, selector: "fire", userInfo: nil, repeats: true)
    }
    
    class func schedule(intervalFromNow: NSTimeInterval, block: () -> ()) -> NSTimer {
        let timer = NSTimer(intervalFromNow, block)
        NSRunLoop.currentRunLoop().addTimer(timer, forMode: NSDefaultRunLoopMode)
        return timer
    }
    
    class func schedule(every interval: NSTimeInterval, block: () -> ()) -> NSTimer {
        let timer = NSTimer(every: interval, block)
        NSRunLoop.currentRunLoop().addTimer(timer, forMode: NSDefaultRunLoopMode)
        return timer
    }
}

time.swift

import Foundation

extension Int {
    var second:  NSTimeInterval { return NSTimeInterval(self) }
    var seconds: NSTimeInterval { return NSTimeInterval(self) }
    var minute:  NSTimeInterval { return NSTimeInterval(self * 60) }
    var minutes: NSTimeInterval { return NSTimeInterval(self * 60) }
    var hour:    NSTimeInterval { return NSTimeInterval(self * 3600) }
    var hours:   NSTimeInterval { return NSTimeInterval(self * 3600) }
}

extension Double {
    var second:  NSTimeInterval { return self }
    var seconds: NSTimeInterval { return self }
    var minute:  NSTimeInterval { return self * 60 }
    var minutes: NSTimeInterval { return self * 60 }
    var hour:    NSTimeInterval { return self * 3600 }
    var hours:   NSTimeInterval { return self * 3600 }
}