Using CleanroomBridging

TargetAction

The TargetAction class allows you to use a Swift closure wherever a standard Cocoa target (id) and action (SEL) pair can be used.

The closure can take zero or one arguments, as is typical with the target/action paradigm.

Example: A UIButton action

You can use a TargetAction instance to set up UIButton action handler in conjunction with the addTarget(_:, action:, forControlEvents:) function declared as part of the UIControl superclass of UIButton:

func addActionHandlerForButton(button: UIButton)
{
    let handler = TargetAction() { (argument: AnyObject?) -> Void in
        let button = argument as? UIButton
        println("Button tapped: \(button?.description)")
    }

    button.addTarget(handler.target, action: handler.action, forControlEvents: .TouchUpInside)
}

The function above sets up a handler that will print out information about button when it is tapped.

Note that the closure passed to the TargetAction constructor takes an argument. In the case of a UIControl target/action, the argument’s value will be the control sending the action.

Example: An NSTimer action

let clock = TargetAction() {
    println("The time is now \(NSDate())")
}

let timer = NSTimer.scheduledTimerWithTimeInterval(1.0,
                                           target: clock.target, 
                                         selector: clock.action,
                                         userInfo: nil,
                                          repeats: true)

The example above sets up a timer that will result in the current time being printed to the console every second.