Swift上的块(animateWithDuration:动画:完成:)

Question

我无法让这些块在Swift上工作.这是一个有效的例子(没有完成块):

UIView.animateWithDuration(0.07) {
    self.someButton.alpha = 1
}

或者没有尾随封闭:

UIView.animateWithDuration(0.2, animations: {
    self.someButton.alpha = 1
})

但是一旦我尝试添加完成块,它就无法工作:

UIView.animateWithDuration(0.2, animations: {
    self.blurBg.alpha = 1
}, completion: {
    self.blurBg.hidden = true
})

自动完成功能给了我completion: ((Bool) -> Void)?但不确定如何使它工作.也尝试使用尾随闭包,但得到了同样的错误:

! Could not find an overload for 'animateWithDuration that accepts the supplied arguments

Swift 3/4更新:

// This is how I do regular animation blocks
UIView.animate(withDuration: 0.2) {
    <#code#>
}

// Or with a completion block
UIView.animate(withDuration: 0.2, animations: {
    <#code#>
}, completion: { _ in
    <#code#>
})

我没有使用尾随闭合来完成块,因为我认为它缺乏清晰度,但如果你喜欢它,那么你可以在下面看到Trevor的答案.

Answer 1

animateWithDuration中的completion参数采用一个带有一个布尔参数的块.在swift中,就像在Obj C块中一样,您必须指定闭包所采用的参数:

UIView.animateWithDuration(0.2, animations: {
    self.blurBg.alpha = 1
}, completion: {
    (value: Bool) in
    self.blurBg.hidden = true
})

这里的重要部分是(value: Bool) in.这告诉编译器这个闭包采用Bool标记为'value'并返回void.

作为参考,如果你想编写一个返回bool的闭包,那么语法就是

{(value: Bool) -> bool in
    //your stuff
}

Answer 2

完成是正确的,闭包必须接受一个Bool参数:(Bool) -> ().尝试

UIView.animate(withDuration: 0.2, animations: {
    self.blurBg.alpha = 1
}, completion: { finished in
    self.blurBg.hidden = true
})

Answer 3

与in关键字一起单独下划线会忽略输入

UIView.animateWithDuration(0.2, animations: {
    self.blurBg.alpha = 1
}, completion: { _ in
    self.blurBg.hidden = true
})

Answer 4

根据上面接受的答案,上面有我的解决方案.它淡出一个视图并隐藏它几乎几乎看不见.

func animateOut(view:UIView) {

    UIView.animateWithDuration (0.25, delay: 0.0, options: UIViewAnimationOptions.CurveLinear ,animations: {
        view.layer.opacity = 0.1
        }, completion: { _ in
            view.hidden = true
    })   
}