将功能传递给完成处理程序

Question

我有一个在视图上执行动画的功能。我想为此函数实现一个完成处理程序，该处理程序将在动画完成后调用。

在ViewController中...

hudView.hide(animated: true, myCompletionHandler: {
    // Animation is complete
})

在HudView类中...

func hide(animated: Bool, myCompletionHandler: () -> Void) {
    if animated {
        transform = CGAffineTransform(scaleX: 0.7, y: 0.7)

        UIView.animate(withDuration: 0.3, delay: 0, usingSpringWithDamping: 0.7, initialSpringVelocity: 0.5, options: [], animations: {
            self.alpha = 0
            self.transform = CGAffineTransform.identity
        }, completion: nil) // I want to run 'myCompletionHandler' in this completion handler
    }
}

我尝试了很多方法，但找不到正确的语法：

}, completion: myCompletionHandler)

传递非转义参数“myCompletionHandler”到函数，期望一个@转义闭包

}, completion: myCompletionHandler())

无法将“Void”类型的值转换为预期的参数类型“((Bool) -

}, completion: { myCompletionHandler() })

闭包：使用非转义参数“myCompletionHandler”可能允许其转义

作为一个快速的新手，这些错误消息对我来说并不重要，我似乎找不到任何正确方法的示例。

将myCompletionHandler传递给的正确方法是什么。是否为完成处理程序设置动画？




Answer 1

You can create your function as,

func hide(_ animated:Bool, completionBlock:((Bool) -> Void)?){

}

And you can call it as,

self.hide(true) { (success) in
   // callback here     
}

Answer 2

这是如何在UIView.animate中使用完成功能:

func hide(animated: Bool, myCompletionHandler: () -> Void) {
    if animated {
        transform = CGAffineTransform(scaleX: 0.7, y: 0.7)

        UIView.animate(withDuration: 0.3, delay: 0, usingSpringWithDamping: 0.7, initialSpringVelocity: 0.5, options: [], animations: {
            self.alpha = 0
            self.transform = CGAffineTransform.identity
        }, completion: { (success) in
            myCompletionHandler()
        })
    }
}

Answer 3

如果要将自己的闭包作为输入参数传递给UIView。要设置动画，您需要匹配闭包的类型，因此myCompletionHandler必须具有类型（（Bool）-

func hide(animated: Bool, myCompletionHandler: ((Bool) -> ())?) {
    if animated {
        transform = CGAffineTransform(scaleX: 0.7, y: 0.7)

        UIView.animate(withDuration: 0.3, delay: 0, usingSpringWithDamping: 0.7, initialSpringVelocity: 0.5, options: [], animations: {
            self.alpha = 0
            self.transform = CGAffineTransform.identity
        }, completion: myCompletionHandler) // I want to run 'myCompletionHandler' in this completion handler
    }
}

你可以这样称呼它：

hudView.hide(animated: true, myCompletionHandler: { success in
    //animation is complete
})