Question

==> swift 3版本可以正常工作，但swift 4和swift 4.2现在可以工作。

static func animate(_ duration: TimeInterval,
                    animations: (() -> Void)!,
                    delay: TimeInterval = 0,
                    options: UIViewAnimationOptions = [],
                    withComplection completion: (() -> Void)! = {}) {

    UIView.animate(
        withDuration: duration,
        delay: delay,
        options: options,
        animations: {
            animations()
        }, completion: { finished in
            completion()
    })
}

static func animateWithRepeatition(_ duration: TimeInterval,
                                   animations: (() -> Void)!,
                                   delay: TimeInterval = 0,
                                   options: UIViewAnimationOptions = [],
                                   withComplection completion: (() -> Void)! = {}) {

    var optionsWithRepeatition = options
    optionsWithRepeatition.insert([.autoreverse, .repeat])

    self.animate(
        duration,
        animations: {
            animations()
        },
        delay:  delay,
        options: optionsWithRepeatition,
        withComplection: { finished in
            completion()
    })
}

在xcode上显示错误=>

无法将类型'（_）-> Void'的值转换为预期的参数类型 '（（（）-> Void）？'

Answer 1

您声明了animate函数，使得其completion参数不包含任何输入参数。但是，当您在finished中调用该函数时，您试图在闭包中调用输入参数animateWithRepetition。只需删除finished，您的代码即可正常编译。

static func animateWithRepetition(_ duration: TimeInterval, animations: (() -> Void)!, delay: TimeInterval = 0, options: UIView.AnimationOptions = [], withComplection completion: (() -> Void)! = {}) {

    var optionsWithRepetition = options
    optionsWithRepeatition.insert([.autoreverse, .repeat])

    self.animate(duration, animations: {
        animations()
    }, delay: delay, options: optionsWithRepeatition, withCompletion: {
        completion()
    })
}

P.S .：我已纠正您输入参数名称中的错字。传递隐式展开类型的输入参数也没有多大意义。将animations设置为普通的Optional并安全地将其拆开，或者将其改成非Optional（如果它永远不应该是nil）。

Answer 2

在函数声明中：

static func animate(_ duration: TimeInterval,
                    animations: (() -> Void)!,
                    delay: TimeInterval = 0,
                    options: UIViewAnimationOptions = [],
                    withComplection completion: (() -> Void)! = {})

您已将完成处理程序定义为(() -> Void)!，即它没有任何参数。

但是当您调用此函数时：

self.animate(
        duration,
        animations: {
            animations()
        },
        delay:  delay,
        options: optionsWithRepeatition,
        withComplection: { finished in
            completion()
    })

您正在完成块中提供参数finished。这就是为什么它给出错误。

swift 4.2无法将类型'（_）-> Void'的值转换为预期的参数类型'（（）-> Void）吗？

2 个答案: