A port of Kotlin's scope functions to Swift.

ScopeFuncs.swift

protocol ScopeFunc {}
extension ScopeFunc {
    @inline(__always) func apply(block: (Self) -> ()) -> Self {
        block(self)
        return self
    }
    @inline(__always) func letIt<R>(block: (Self) -> R) -> R {
        return block(self)
    }
}
extension NSObject: ScopeFunc {}

usage.swift

let imageView = UIImageView().apply {
    $0.contentMode = .ScaleAspectFit
    $0.opaque = true
    $0.frame = CGRectMake(...)
    $0.setImageWithURL(NSURL(string: "..."))
}

CAKeyframeAnimation(keyPath: "transform.rotation").apply {
    $0.beginTime = CACurrentMediaTime()+delay
    $0.duration = 0.2
    $0.repeatCount = 10
    $0.values = [ 0.005*M_PI, -0.005*M_PI, 0.005*M_PI ]
    
    imageView.layer.addAnimation($0, forKey: "wiggle")
}

@Guang1234567 the use of the Int constructor is just for the purpose of illustration, the point is that let can useful with optional chaining.