Swift 4 添加手势:覆盖 vs @objc [英] Swift 4 add gesture: override vs @objc

问题描述

我希望在我的视图中添加一个手势，如下所示:

I'm looking to add a gesture to my view as follows:

    override func viewDidLoad() {
    super.viewDidLoad()

    < blah blah blah >

    // Add tap gesture
    let tap = UITapGestureRecognizer(target: self, action: #selector(handleTap))
    myView.addGestureRecognizer(tap)
}

但是，在 Swift 4 中，我的编译器给了我以下错误:

However, in Swift 4 my compiler is giving me the following error:

Argument of '#selector' refers to instance method 'handleTap()' that is not exposed to Objective-C

建议添加@objc，将这个实例方法暴露给Objective-C.

The suggestion is to add @objc to expose this instance method to Objective-C.

实现此功能的另一个选项(仅通过代码)是覆盖 touchesBegan() 函数并使用它来处理点击.

The other option to implement this (through code only) would be to override the touchesBegan() function and use that to handle the tap.

我正在尝试以Swift"方式执行此操作，而无需引入 Obj-C.是否有一种纯粹的 Swift 方法可以在不使用 @objc 的情况下添加这个点击手势?或者这是添加此点击手势的正常和预期方式?

I am trying to do this the 'Swift' way without having to bring in Obj-C. Is there a pure Swift way to add this tap gesture without using @objc? Or is that the normal and intended way of adding this tap gesture?

推荐答案

使用 @objc 这里是正常的和预期的方式.

Using @objc here is the normal and intended way.

底层的手势识别器代码是用 Objective-C 编写的，所以你需要让你的选择器可以从 Objective-C 调用，这就是 @objc 所做的.

The underlying gesture recogniser code is written in Objective-C so you need to make your selector callable from Objective-C and that is all @objc is doing.

您的替代技术仍然使用 Objective C-API，但在没有选择器的情况下与它们交互，因此它不太明显.

Your alternative technique is still using Objective C-APIs, but interacting with them without selectors so it is just less visible.

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