Swift 3 NSNotificationCenter Keyboardwillshow/hide

Question

我有一段代码在 Swift 2 中有效，我尝试使用 Xcode 将代码更新到最新版本，我修复了除两个问题之外的所有问题。

我有这个代码：

let loginvc: LoginVC = self.storyboard?.instantiateViewController(withIdentifier: "LoginVC") as! LoginVC
NotificationCenter.defaultCenter().addObserver(self, selector: #selector(LoginViewController.keyboardWillShow(_:)), name: UIKeyboardWillShowNotification, object: nil)
NotificationCenter.defaultCenter().addObserver(self, selector: #selector(LoginViewController.keyboardWillHide(_:)), name: UIKeyboardWillHideNotification, object: nil)

与此配对：

func keyboardWillShow(notification: NSNotification) {

    constraint.constant = -100
    UIView.animate(withDuration: 0.3) {
        self.view.layoutIfNeeded()
    }
}

func keyboardWillHide(notification: NSNotification) {

    constraint.constant = 25
    UIView.animate(withDuration: 0.3) {
        self.view.layoutIfNeeded()
    }
}

在第一部分我现在收到一条错误消息

Type 'LoginViewController' has no member 'keyboardWillShow/Hide'

我不明白为什么它没有看到下面的方法。

有人知道这个问题的解决方案吗？

Answer 1

查看更新后的 Swift Programming Language book。第 1027 和 1028 页就是您要查找的内容。它应该是这样的：

func keyboardWillHide(_ notification: NSNotification) {…

注意上面的附加下划线。还有：

#selector(LoginViewController.keyboardWillHide(_:))

您可能还需要将 @objc(keyboardWillHideWithNotification:) 添加到您的 class。

Answer 2

NSNotificationCenter 更改了获取显示键盘的内容：

NotificationCenter.default.addObserver(self, selector: #selector(NovaVisitaVC.abreTeclado(notification:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)

NotificationCenter.default.addObserver(self, selector: #selector(NovaVisitaVC.abreTeclado(notification:)), name: NSNotification.Name.UIKeyboardWillHide, object: nil)

Answer 3

使用适用于 swift3 的代码

您可以使用 ViewController（例如 loginvc）添加通知

let loginvc : LoginVC = self.storyboard?.instantiateViewController(withIdentifier: "LoginVC") as! LoginVC

    NotificationCenter.default.addObserver(self,
        selector: #selector(loginvc.keyboardWillShow(notification:)),
        name: NSNotification.Name.UIKeyboardWillShow, object: nil)
    NotificationCenter.default.addObserver(self,
        selector: #selector(loginvc.keyboardWillHide(notification:)),
        name: NSNotification.Name.UIKeyboardWillHide, object: nil)

然后添加键盘隐藏和显示方法

func keyboardWillShow(notification: NSNotification) {
    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        print("Show") 
    }
}
func keyboardWillHide(notification: NSNotification) {
    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        print("Hide")
    }
}

Answer 4

在 Swift 4.2 上，NSNotificationCenter 的 addObserver 名称也发生了变化：

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(notification:)), name: UIResponder.keyboardDidShowNotification, object: nil)

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(notification:)), name: UIResponder.keyboardDidHideNotification, object: nil)

Swift 3 NSNotificationCenter Keyboardwillshow/hide

Swift 3 NSNotificationCenter Keyboardwillshow/hide

nsnotificationcenter

ios

swift

swift3