协议未触发

Question

我的协议根本没有触发，我正在使它符合我希望它触发的方法。任何帮助将不胜感激！

public class NoteCardView:UIView {
@IBInspectable var delegate: NoteCardViewDelegate?

 func handleTitleLabelTap(_ recognizer:UITapGestureRecognizer) {
    // Verified this function is being called and has the right value!
self.delegate?.noteCardViewTitleLabelDidRecieveTap(MainViewController.NoteCardArray[Int(recognizer.view!.tag)])
 }
}

public protocol NoteCardViewDelegate {
// This should be being fired..
func noteCardViewTitleLabelDidRecieveTap(_ view: NoteCardView!)
}

extension MainViewController: NoteCardViewDelegate {
// this is what the handleTitleLabelTap function should do!
func noteCardViewTitleLabelDidRecieveTap(_ view: NoteCardView!) {
    print("6")
    let card:NoteCardView = (view)
    UIView.animate(withDuration: 0.5, delay: 0.0, options: UIViewAnimationOptions.curveEaseInOut, animations: {

        card.contentView.leftAnchor.constraint(equalTo: view.leftAnchor, constant: (self.elementPlacement / 4) + 20)

        card.contentView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: 100)

    }, completion: { (finished: Bool) in

        self.elementPlacement = (self.elementPlacement + 1)
        card.titleLabelTapGestureRecognizer!.isEnabled = !(self.elementPlacement == 5)
    })
}
}

Answer 1

这一行：

self.delegate?.noteCardViewTitleLabelDidRecieveTap(MainViewController.NoteCardArray[Int(recognizer.view!.tag)])

...如果 self.delegate 为 nil，则不会做任何事情。这 ”？”告诉编译器检查 nil 并在 is nil 时停止。

我建议添加打印语句：

print("About to call delegate. delegate = \(delegate)") delegate?.noteCardViewTitleLabelDidRecieveTap(MainViewController.NoteCardArray[Int(recognizer.view!.tag)])

顺便说一句，self 是不需要的，你应该省略它。您通常需要指定 self 的唯一一次是在闭包中，编译器坚持将其包含在内以“使捕获语义显式”。我的建议是除非编译器抱怨，否则不要使用它。

还要注意，说“我的协议没有触发”是没有意义的。协议是商定的一组方法/属性。它就像一种用于在理解协议的对象之间进行通信的术语。最好说“我的委托方法没有被调用。”