Swift以编程方式为带按钮的按钮创建函数

概述在 Swift中,您可以为这样的按钮创建一个函数： button.addTarget(self, action: #selector(buttonAction), forControlEvents: .TouchUpInside) 但有没有办法可以做到这样的事情： button.whenButtonIsClicked({Insert code here}) 这样我甚至没有为按钮声明一个显式函数.我 在 Swift中,您可以为这样的按钮创建一个函数：

button.addTarget(self,action: #selector(buttonAction),forControlEvents: .touchUpInsIDe)

但有没有办法可以做到这样的事情：

button.whenbuttonIsClicked({Insert code here})

这样我甚至没有为按钮声明一个显式函数.我知道我可以使用按钮标签,但我更愿意这样做.

解决方法 创建自己的UIbutton子类来执行此 *** 作：

class Mybutton: UIbutton {    var action: (() -> VoID)?    func whenbuttonIsClicked(action: @escaPing () -> VoID) {        self.action = action        self.addTarget(self,action: #selector(Mybutton.clicked),for: .touchUpInsIDe)    }    // button Event Handler:    // I have not marked this as @IBAction because it is not intended to    // be hooked up to Interface Builder           @objc func clicked() {        action?()    }}

当您以编程方式创建按钮然后调用whenbuttonIsClicked来设置其功能时,将Mybutton替换为UIbutton.

您还可以在故事板中使用UIbuttons(只需将其类更改为Mybutton),然后在vIEwDIDLoad中调用whenbuttonIsClicked.

@IBOutlet weak var thebutton: Mybutton!var count = 0overrIDe func vIEwDIDLoad() {    super.vIEwDIDLoad()    // be sure to declare [uNowned self] if you access    // propertIEs or methods of the class so that you    // don't create a strong reference cycle    thebutton.whenbuttonIsClicked { [uNowned self] in        self.count += 1        print("count = \(self.count)")    }

一个更有能力的实施

认识到程序员可能想要处理比.touchUpInsIDe更多的事件这一事实,我写了这个更强大的版本,它支持每个UIbutton的多个闭包和每个事件类型的多个闭包.

class Closurebutton: UIbutton {    private var actions = [UInt : [((UIControl.Event) -> VoID)]]()    private let funcDict: [UInt : Selector] = [        UIControl.Event.touchCancel.rawValue:       #selector(eventtouchCancel),UIControl.Event.touchDown.rawValue:         #selector(eventtouchDown),UIControl.Event.touchDownRepeat.rawValue:   #selector(eventtouchDownRepeat),UIControl.Event.touchUpInsIDe.rawValue:     #selector(eventtouchUpInsIDe),UIControl.Event.touchUpOutsIDe.rawValue:    #selector(eventtouchUpOutsIDe),UIControl.Event.touchdragenter.rawValue:    #selector(eventtouchdragenter),UIControl.Event.touchDragExit.rawValue:     #selector(eventtouchDragExit),UIControl.Event.touchDragInsIDe.rawValue:   #selector(eventtouchDragInsIDe),UIControl.Event.touchDragOutsIDe.rawValue:  #selector(eventtouchDragOutsIDe)    ]    func handle(events: [UIControl.Event],action: @escaPing (UIControl.Event) -> VoID) {        for event in events {            if var closures = actions[event.rawValue] {                closures.append(action)                actions[event.rawValue] = closures            } else {                guard let sel = funcDict[event.rawValue] else { continue }                self.addTarget(self,action: sel,for: event)                actions[event.rawValue] = [action]            }        }    }    private func callActions(for event: UIControl.Event) {        guard let actions = actions[event.rawValue] else { return }        for action in actions {            action(event)        }    }    @objc private func eventtouchCancel()       { callActions(for: .touchCancel) }    @objc private func eventtouchDown()         { callActions(for: .touchDown) }    @objc private func eventtouchDownRepeat()   { callActions(for: .touchDownRepeat) }    @objc private func eventtouchUpInsIDe()     { callActions(for: .touchUpInsIDe) }    @objc private func eventtouchUpOutsIDe()    { callActions(for: .touchUpOutsIDe) }    @objc private func eventtouchdragenter()    { callActions(for: .touchdragenter) }    @objc private func eventtouchDragExit()     { callActions(for: .touchDragExit) }    @objc private func eventtouchDragInsIDe()   { callActions(for: .touchDragInsIDe) }    @objc private func eventtouchDragOutsIDe()  { callActions(for: .touchDragOutsIDe) }}

演示

class VIEwController: UIVIEwController {    var count = 0    overrIDe func vIEwDIDLoad() {        super.vIEwDIDLoad()        let button = Closurebutton(frame: CGRect(x: 50,y: 100,wIDth: 60,height: 40))        button.setTitle("press me",for: .normal)        button.setTitlecolor(.blue,for: .normal)        // Demonstration of handling a single UIControl.Event type.        // If your closure accesses self,be sure to declare [uNowned self]        // to prevent a strong reference cycle        button.handle(events: [.touchUpInsIDe]) { [uNowned self] _ in            self.count += 1            print("count = \(self.count)")        }        // define a second handler for touchUpInsIDe:        button.handle(events: [.touchUpInsIDe]) { _ in            print("I'll be called on touchUpInsIDe too")        }        let manyEvents: [UIControl.Event] = [.touchCancel,.touchUpInsIDe,.touchDown,.touchDownRepeat,.touchUpOutsIDe,.touchdragenter,.touchDragExit,.touchDragInsIDe,.touchDragOutsIDe]        // Demonstration of handling multiple events        button.handle(events: manyEvents) { event in            switch event {            case .touchCancel:                print("touchCancel")            case .touchDown:                print("touchDown")            case .touchDownRepeat:                print("touchDownRepeat")            case .touchUpInsIDe:                print("touchUpInsIDe")            case .touchUpOutsIDe:                print("touchUpOutsIDe")            case .touchdragenter:                print("touchdragenter")            case .touchDragExit:                print("touchDragExit")            case .touchDragInsIDe:                print("touchDragInsIDe")            case .touchDragOutsIDe:                print("touchDragOutsIDe")            default:                break            }        }        self.vIEw.addSubvIEw(button)    }}

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