Ios 你的意思是什么印刷品（）'；斯威夫特？_Ios_Iphone_Swift_Cocoa Touch

Ios 你的意思是什么印刷品（）'；斯威夫特？

ios iphone swift cocoa-touch

Ios 你的意思是什么印刷品（）'；斯威夫特？,ios,iphone,swift,cocoa-touch,Ios,Iphone,Swift,Cocoa Touch,嗨，我刚开始学斯威夫特。我只是学习ios开发的初学者 func showOkay() { let title = NSLocalizedString("a title", comment: "") let message = NSLocalizedString("msg", comment: "") let cansal = NSLocalizedString("cancel", comment: "") let ok = NSLocalizedString("o

嗨，我刚开始学斯威夫特。我只是学习ios开发的初学者

func showOkay() {
    let title = NSLocalizedString("a title", comment: "")
    let message = NSLocalizedString("msg", comment: "")
    let cansal = NSLocalizedString("cancel", comment: "")
    let ok = NSLocalizedString("ok", comment: "")
    let alertController = UIAlertController (title: title, message: message, preferredStyle: .alert)

    let cancelAlertAction = UIAlertAction (title : cansal, style : .cancel) {
        _ in print("cancel") // i don't understand this line . its just a print or somthing else. why i cant use print here.
    }
    let okAction = UIAlertAction(title: ok , style : .default) {
        _ in print("ok") // i don't understand this line. its just a print or somthing else. why i cant use print here.
    }

    alertController.addAction(cancelAlertAction)
    alertController.addAction(okAction)
    present(alertController, animated: true, completion: nil)
}

@IBAction func btnAction(_ sender: Any) {
     showOkay()
}

如果我使用

print（）

只会给我类似的错误

func showOkay() {
    let title = NSLocalizedString("a title", comment: "")
    let message = NSLocalizedString("msg", comment: "")
    let cansal = NSLocalizedString("cancel", comment: "")
    let ok = NSLocalizedString("ok", comment: "")
    let alertController = UIAlertController (title: title, message: message, preferredStyle: .alert)

    let cancelAlertAction = UIAlertAction (title : cansal, style : .cancel) {
        _ in print("cancel") // i don't understand this line . its just a print or somthing else. why i cant use print here.
    }
    let okAction = UIAlertAction(title: ok , style : .default) {
        _ in print("ok") // i don't understand this line. its just a print or somthing else. why i cant use print here.
    }

    alertController.addAction(cancelAlertAction)
    alertController.addAction(okAction)
    present(alertController, animated: true, completion: nil)
}

@IBAction func btnAction(_ sender: Any) {
     showOkay()
}

无法将类型为“（）->（）”的值转换为所需的参数类型“（（UIAlertAction）->Void）？”

func showOkay() {
    let title = NSLocalizedString("a title", comment: "")
    let message = NSLocalizedString("msg", comment: "")
    let cansal = NSLocalizedString("cancel", comment: "")
    let ok = NSLocalizedString("ok", comment: "")
    let alertController = UIAlertController (title: title, message: message, preferredStyle: .alert)

    let cancelAlertAction = UIAlertAction (title : cansal, style : .cancel) {
        _ in print("cancel") // i don't understand this line . its just a print or somthing else. why i cant use print here.
    }
    let okAction = UIAlertAction(title: ok , style : .default) {
        _ in print("ok") // i don't understand this line. its just a print or somthing else. why i cant use print here.
    }

    alertController.addAction(cancelAlertAction)
    alertController.addAction(okAction)
    present(alertController, animated: true, completion: nil)
}

@IBAction func btnAction(_ sender: Any) {
     showOkay()
}

此语句使用尾部闭包语法。

和

之间的东西实际上是一个闭包，它被传递给

UIAlertAction

，稍后在事件发生时调用。调用闭包时，它将被传递创建的

UIAlertAction

对象

func showOkay() {
    let title = NSLocalizedString("a title", comment: "")
    let message = NSLocalizedString("msg", comment: "")
    let cansal = NSLocalizedString("cancel", comment: "")
    let ok = NSLocalizedString("ok", comment: "")
    let alertController = UIAlertController (title: title, message: message, preferredStyle: .alert)

    let cancelAlertAction = UIAlertAction (title : cansal, style : .cancel) {
        _ in print("cancel") // i don't understand this line . its just a print or somthing else. why i cant use print here.
    }
    let okAction = UIAlertAction(title: ok , style : .default) {
        _ in print("ok") // i don't understand this line. its just a print or somthing else. why i cant use print here.
    }

    alertController.addAction(cancelAlertAction)
    alertController.addAction(okAction)
    present(alertController, animated: true, completion: nil)
}

@IBAction func btnAction(_ sender: Any) {
     showOkay()
}

let cancelAlertAction = UIAlertAction (title : cansal , style : .cancel) {
    _ in print("cancel") \\ i don't understand this line . its just a print or somthing else . why i cant use print here.
}

如果您不打算使用警报操作，则需要中的

\uuu告诉Swift您忽略了UIAlertAction
，并且对其不做任何操作。你是说，我知道有一个参数，但我忽略了它
func showOkay() {
    let title = NSLocalizedString("a title", comment: "")
    let message = NSLocalizedString("msg", comment: "")
    let cansal = NSLocalizedString("cancel", comment: "")
    let ok = NSLocalizedString("ok", comment: "")
    let alertController = UIAlertController (title: title, message: message, preferredStyle: .alert)

    let cancelAlertAction = UIAlertAction (title : cansal, style : .cancel) {
        _ in print("cancel") // i don't understand this line . its just a print or somthing else. why i cant use print here.
    }
    let okAction = UIAlertAction(title: ok , style : .default) {
        _ in print("ok") // i don't understand this line. its just a print or somthing else. why i cant use print here.
    }

    alertController.addAction(cancelAlertAction)
    alertController.addAction(okAction)
    present(alertController, animated: true, completion: nil)
}

@IBAction func btnAction(_ sender: Any) {
     showOkay()
}

如果未在

中指定

，Swift将推断您的闭包类型为（）->（）
类型，这意味着它不获取任何内容，也不生成任何内容。这与您希望提供的闭包类型不匹配，闭包类型为（UIAlertAction）->Void
（采用UIAlertAction
，但不返回任何内容）
func showOkay() {
    let title = NSLocalizedString("a title", comment: "")
    let message = NSLocalizedString("msg", comment: "")
    let cansal = NSLocalizedString("cancel", comment: "")
    let ok = NSLocalizedString("ok", comment: "")
    let alertController = UIAlertController (title: title, message: message, preferredStyle: .alert)

    let cancelAlertAction = UIAlertAction (title : cansal, style : .cancel) {
        _ in print("cancel") // i don't understand this line . its just a print or somthing else. why i cant use print here.
    }
    let okAction = UIAlertAction(title: ok , style : .default) {
        _ in print("ok") // i don't understand this line. its just a print or somthing else. why i cant use print here.
    }

    alertController.addAction(cancelAlertAction)
    alertController.addAction(okAction)
    present(alertController, animated: true, completion: nil)
}

@IBAction func btnAction(_ sender: Any) {
     showOkay()
}

通常是这样写的：
func showOkay() {
    let title = NSLocalizedString("a title", comment: "")
    let message = NSLocalizedString("msg", comment: "")
    let cansal = NSLocalizedString("cancel", comment: "")
    let ok = NSLocalizedString("ok", comment: "")
    let alertController = UIAlertController (title: title, message: message, preferredStyle: .alert)

    let cancelAlertAction = UIAlertAction (title : cansal, style : .cancel) {
        _ in print("cancel") // i don't understand this line . its just a print or somthing else. why i cant use print here.
    }
    let okAction = UIAlertAction(title: ok , style : .default) {
        _ in print("ok") // i don't understand this line. its just a print or somthing else. why i cant use print here.
    }

    alertController.addAction(cancelAlertAction)
    alertController.addAction(okAction)
    present(alertController, animated: true, completion: nil)
}

@IBAction func btnAction(_ sender: Any) {
     showOkay()
}

let cancelAlertAction = UIAlertAction (title : cansal , style : .cancel) { _ in
    print("cancel")
}

这更清楚地表明，

中的

\uuuu是闭包参数语法，与print
语句没有直接关系。
此语句使用尾部闭包语法。{
和}
之间的东西实际上是一个闭包，它被传递给UIAlertAction
，稍后在事件发生时调用。调用闭包时，它将被传递创建的UIAlertAction
对象
func showOkay() {
    let title = NSLocalizedString("a title", comment: "")
    let message = NSLocalizedString("msg", comment: "")
    let cansal = NSLocalizedString("cancel", comment: "")
    let ok = NSLocalizedString("ok", comment: "")
    let alertController = UIAlertController (title: title, message: message, preferredStyle: .alert)

    let cancelAlertAction = UIAlertAction (title : cansal, style : .cancel) {
        _ in print("cancel") // i don't understand this line . its just a print or somthing else. why i cant use print here.
    }
    let okAction = UIAlertAction(title: ok , style : .default) {
        _ in print("ok") // i don't understand this line. its just a print or somthing else. why i cant use print here.
    }

    alertController.addAction(cancelAlertAction)
    alertController.addAction(okAction)
    present(alertController, animated: true, completion: nil)
}

@IBAction func btnAction(_ sender: Any) {
     showOkay()
}

let cancelAlertAction = UIAlertAction (title : cansal , style : .cancel) {
    _ in print("cancel") \\ i don't understand this line . its just a print or somthing else . why i cant use print here.
}

如果您不打算使用警报操作，则需要

中的

\uuu告诉Swift您忽略了UIAlertAction
，并且对其不做任何操作。你是说，我知道有一个参数，但我忽略了它
func showOkay() {
    let title = NSLocalizedString("a title", comment: "")
    let message = NSLocalizedString("msg", comment: "")
    let cansal = NSLocalizedString("cancel", comment: "")
    let ok = NSLocalizedString("ok", comment: "")
    let alertController = UIAlertController (title: title, message: message, preferredStyle: .alert)

    let cancelAlertAction = UIAlertAction (title : cansal, style : .cancel) {
        _ in print("cancel") // i don't understand this line . its just a print or somthing else. why i cant use print here.
    }
    let okAction = UIAlertAction(title: ok , style : .default) {
        _ in print("ok") // i don't understand this line. its just a print or somthing else. why i cant use print here.
    }

    alertController.addAction(cancelAlertAction)
    alertController.addAction(okAction)
    present(alertController, animated: true, completion: nil)
}

@IBAction func btnAction(_ sender: Any) {
     showOkay()
}

如果未在

中指定

，Swift将推断您的闭包类型为（）->（）
类型，这意味着它不获取任何内容，也不生成任何内容。这与您希望提供的闭包类型不匹配，闭包类型为（UIAlertAction）->Void
（采用UIAlertAction
，但不返回任何内容）
func showOkay() {
    let title = NSLocalizedString("a title", comment: "")
    let message = NSLocalizedString("msg", comment: "")
    let cansal = NSLocalizedString("cancel", comment: "")
    let ok = NSLocalizedString("ok", comment: "")
    let alertController = UIAlertController (title: title, message: message, preferredStyle: .alert)

    let cancelAlertAction = UIAlertAction (title : cansal, style : .cancel) {
        _ in print("cancel") // i don't understand this line . its just a print or somthing else. why i cant use print here.
    }
    let okAction = UIAlertAction(title: ok , style : .default) {
        _ in print("ok") // i don't understand this line. its just a print or somthing else. why i cant use print here.
    }

    alertController.addAction(cancelAlertAction)
    alertController.addAction(okAction)
    present(alertController, animated: true, completion: nil)
}

@IBAction func btnAction(_ sender: Any) {
     showOkay()
}

通常是这样写的：
func showOkay() {
    let title = NSLocalizedString("a title", comment: "")
    let message = NSLocalizedString("msg", comment: "")
    let cansal = NSLocalizedString("cancel", comment: "")
    let ok = NSLocalizedString("ok", comment: "")
    let alertController = UIAlertController (title: title, message: message, preferredStyle: .alert)

    let cancelAlertAction = UIAlertAction (title : cansal, style : .cancel) {
        _ in print("cancel") // i don't understand this line . its just a print or somthing else. why i cant use print here.
    }
    let okAction = UIAlertAction(title: ok , style : .default) {
        _ in print("ok") // i don't understand this line. its just a print or somthing else. why i cant use print here.
    }

    alertController.addAction(cancelAlertAction)
    alertController.addAction(okAction)
    present(alertController, animated: true, completion: nil)
}

@IBAction func btnAction(_ sender: Any) {
     showOkay()
}

let cancelAlertAction = UIAlertAction (title : cansal , style : .cancel) { _ in
    print("cancel")
}

这更清楚地表明，

中的

\是闭包参数语法，与print
语句没有直接关系
func showOkay() {
    let title = NSLocalizedString("a title", comment: "")
    let message = NSLocalizedString("msg", comment: "")
    let cansal = NSLocalizedString("cancel", comment: "")
    let ok = NSLocalizedString("ok", comment: "")
    let alertController = UIAlertController (title: title, message: message, preferredStyle: .alert)

    let cancelAlertAction = UIAlertAction (title : cansal, style : .cancel) {
        _ in print("cancel") // i don't understand this line . its just a print or somthing else. why i cant use print here.
    }
    let okAction = UIAlertAction(title: ok , style : .default) {
        _ in print("ok") // i don't understand this line. its just a print or somthing else. why i cant use print here.
    }

    alertController.addAction(cancelAlertAction)
    alertController.addAction(okAction)
    present(alertController, animated: true, completion: nil)
}

@IBAction func btnAction(_ sender: Any) {
     showOkay()
}