Swift 3 NSNotificationCenter KeyboardWill显示/隐藏

Question

我有一段代码在Swift 2中工作,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内容

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()
    }
}

在第一部分我现在得到一个错误说"类型'LoginViewController'没有成员'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

查看更新的Swift Programming Language一书.第1027和1028页是您正在寻找的.它应该是这样的:

func keyboardWillHide(_ notification: NSNotification) {…

请注意上面的附加下划线.也:

#selector(LoginViewController.keyboardWillHide(_:))

您可能还需要添加@objc(keyboardWillHideWithNotification:)到您的班级.

Answer 2

在Swift 4.2上，NSNotificationCenter的addObserver名称也已更改：

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)