NSTimer extension which breaks the retain cycle in Swift.

nstimer_break_retain.swift

private class Block<T> {
    let f : T
    init (_ f: T) { self.f = f }
}

extension NSTimer {
    static func xxx_scheduledTimerWithTimeInterval(ti: NSTimeInterval, block: ()->(), repeats: Bool) -> NSTimer {
        return self.scheduledTimerWithTimeInterval(ti, target:
            self, selector: "xxx_blcokInvoke:", userInfo: Block(block), repeats: repeats)
    }
    
    static func xxx_blcokInvoke(timer: NSTimer) {
        if let block = timer.userInfo as? Block<()->()> {
            block.f()
        }
    }
}