ios - 带有按钮和选择器的协议(protocol)扩展

Question

我有一些协议(protocol):

@objc protocol SomeProtocol { } 

我为 UIViewController 实例扩展。在此扩展中，我想创建并添加一个按钮，其选择器也在协议(protocol)中定义:

extension SomeProtocol where Self: UIViewController {

    func addSomeButton() {
        let someButton = UIButton()
        someButton.addTarget(self, #selector(someButtonPressed), for: .touchUpInside)
        view.addSubview(someButton)
    }

    @objc func someButtonPressed() {
    }

}

但是，我在 someButtonPressed 的定义处收到错误消息:@objc 只能与类成员、@objc 协议(protocol)和类的具体扩展一起使用。

有什么方法可以使用协议(protocol)来实现吗？

提前感谢您的任何建议!

Answer 1

解决方法是向 UIButton 添加一个闭合 socket ，而不是此处所示的目标操作 https://stackoverflow.com/a/41438789/5058116并为方便起见复制在下面。

typealias Closure = () -> ()

///
class ClosureSleeve {
    let closure: Closure
    init(_ closure: @escaping Closure) {
        self.closure = closure
    }
    @objc func invoke () {
        closure()
    }
}

extension UIControl {
    func addAction(for controlEvents: UIControl.Event = .touchUpInside, _ closure: @escaping Closure) {
        let sleeve = ClosureSleeve(closure)
        addTarget(sleeve, action: #selector(ClosureSleeve.invoke), for: controlEvents)
        objc_setAssociatedObject(self, String(format: "[%d]", arc4random()), sleeve, objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN)
    }
}

然后简单地替换:

someButton.addTarget(self, #selector(someButtonPressed), for: .touchUpInside)

与:

someButton.addAction { [weak self] in
        self?.someButtonPressed()
    }

嘿嘿。