UIButton block equivalent to addTarget:action:forControlEvents: method?

Question

I looked around, but couldn\'t find this on the internet, nor anywhere in the Apple docs, so I\'m guessing it doesn\'t exist.

But is there a iOS4 blocks equivalent A

Answer 1

Swift extension / category based implementation that I whipped up. Using OBJC associated objects is not an anti-pattern. :P

import UIKit

// MARK: UIControl Block based actions
typealias ActionBlock = (UIControl) -> ()

class UIButtonActionDelegate : NSObject {
    let actionBlock : ActionBlock
    init(actionBlock: ActionBlock) {
        self.actionBlock = actionBlock
    }
    func triggerBlock(control : UIControl) {
        actionBlock(control)
    }
}

private var actionHandlersKey: UInt8 = 0
extension UIControl {
    var actionHandlers: NSMutableArray { // cat is *effectively* a stored property
        get {
            return associatedObject(self, key: &actionHandlersKey, initialiser: { () -> NSMutableArray in
                return NSMutableArray()
            })
        }
        set { associateObject(self, key: &actionHandlersKey, value: newValue) }
    }

    func addBlockForEvents(events: UIControlEvents, block: ActionBlock) {
        let actionDelegate = UIButtonActionDelegate(actionBlock: block)
        actionHandlers.addObject(actionDelegate) // So it gets retained
        addTarget(actionDelegate, action: #selector(UIButtonActionDelegate.triggerBlock(_:)), forControlEvents: events)
    }
}

// MARK: Associated Object wrapper

func associatedObject(
    base: AnyObject,
    key: UnsafePointer,
    initialiser: () -> ValueType)
    -> ValueType {
        if let associated = objc_getAssociatedObject(base, key)
            as? ValueType { return associated }
        let associated = initialiser()
        objc_setAssociatedObject(base, key, associated,
                                 .OBJC_ASSOCIATION_RETAIN)
        return associated
}

func associateObject(
    base: AnyObject,
    key: UnsafePointer,
    value: ValueType) {
    objc_setAssociatedObject(base, key, value,
                             .OBJC_ASSOCIATION_RETAIN)
}