A Block (Closure) as a Class Property in Swift

An example of using a block (closure) as a class property in Swift.

class ChatViewController: UIViewController {

    private var someClosure: (() -> Void)?
    private var anotherClosure: ((arg: Double) -> Bool)?

    func executeClosures() {
        if self.someClosure != nil {
            self.someClosure()
        }

        if self.anotherClosure != nil {
            let boolResult = self.anotherClosure(arg: 2.0)
        }
    }

    func addSelfClosure(closure: (() -> Void)!) {
        self.someClosure = closure
    }

    func printSomething() {
        self.addSelfClosure() {
            print("closure called")
        }
        self.executeClosures() // prints: closure called
    }

}