Swift：来自UIViewController扩展的registerForKeyboardNotifications

Question

我正在尝试清理我的代码并创建和扩展到UIViewController以注册和取消注册我的键盘。 在我的实用程序文件中，我有以下内容：

extension UIViewController {
     //Register the keyboard for notifications in  viewDidLoad
     func registerForKeyboardNotifications() {

         //Adding notifies on keyboard appearing
         NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(CreateEventVC.keyboardWasShown(_:)), name: UIKeyboardWillShowNotification, object: nil) 
         NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(CreateEventVC.keyboardWillBeHidden(_:)), name: UIKeyboardWillHideNotification, object: nil)

     }

     //Deregister the keyboard for notification in viewWillDisapper
     func deregisterFromKeyboardNotifications() {

         //Removing notifies on keyboard appearing
         NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillShowNotification, object: nil)
         NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillHideNotification, object: nil)
     }
}

我需要的是selector的“CreateEventVC”作为当前的Class 。

然后我用我的ViewController调用它，如下所示：

override func viewDidLoad() {
         super.viewDidLoad()

         //Register Keyboard
         registerForKeyboardNotifications()
}

override func viewWillDisappear(animated: Bool) {

    deregisterFromKeyboardNotifications()

}

func keyboardWasShown(notification: NSNotification) {

    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {

        self.view.frame.origin.y -= keyboardSize.height

    }

}

func keyboardWillBeHidden(notification: NSNotification) {

    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {

        self.view.frame.origin.y += keyboardSize.height

    }

}

我觉得这不是最好的做法。 任何帮助或建议都会很棒！

Answer 1

我正在使用UIViewController和UIScrollView扩展。 如果您正在移动UIView您也可以使用此扩展，但使用UIScrollView更方便，因为它不会弄乱您的视图边界，如果您需要添加更多文本字段，这种方法更通用。

extension UIViewController {
    func registerForKeyboardDidShowNotification(usingBlock block: ((NSNotification, CGSize) -> Void)? = nil) {
        NSNotificationCenter.defaultCenter().addObserverForName(UIKeyboardDidShowNotification, object: nil, queue: nil, usingBlock: { (notification) -> Void in
            let userInfo = notification.userInfo!
            guard let keyboardSize = userInfo[UIKeyboardFrameBeginUserInfoKey]?.CGRectValue.size else { fatalError("Can't grab the keyboard frame") }

            block?(notification, keyboardSize)
        })
    }

    func registerForKeyboardWillHideNotification(usingBlock block: (NSNotification -> Void)? = nil) {
        NSNotificationCenter.defaultCenter().addObserverForName(UIKeyboardWillHideNotification, object: nil, queue: nil, usingBlock: { (notification) -> Void in
            block?(notification)
        })
    }
}

所以使用这段代码，在你的UIViewController的viewDidLoad()方法中，你可以注册键盘通知并在块中添加任何其他功能。 像这样：

override func viewDidLoad() {
    super.viewDidLoad()

    registerForKeyboardDidShowNotification { notif, size in
        self.view.frame.origin.y -= size.height
    }

    registerForKeyboardWillHideNotification { notif in
        self.view.frame.origin.y = 0
    }
}

---

编辑:(对于UIScrollView ）

1）你能为键盘显示动画吗？

实际上键盘外观总是动画的，所以我认为你说的是​​scrollview调整。 是的你可以。 下面我发布了更新的UIViewController和UIScrollView扩展，它们正在处理它。

2）我是否需要取消注册键盘？

那么，避免将来发生崩溃是一种很好的做法。 为此，您可能更愿意在viewWillAppear添加通知，并在viewWillDisappear方法中将其删除。

    NSNotificationCenter.defaultCenter().removeObserver(scrollView, name: UIKeyboardDidShowNotification, object: nil)
    NSNotificationCenter.defaultCenter().removeObserver(scrollView, name: UIKeyboardWillHideNotification, object: nil)

3）对于UIScrollView方法，我将所有对象放在屏幕的滚动视图中，然后只需在每个UITextField成为第一个响应者时以编程方式滚动视图？

您不以编程方式滚动任何内容。 你需要做的是改变UIScrollView的插图，它会自动使第一个响应者在屏幕上可见。

这是我在项目中使用的代码：

extension UIViewController {
    func registerForKeyboardDidShowNotification(scrollView: UIScrollView, usingBlock block: (CGSize? -> Void)? = nil) {
        NSNotificationCenter.defaultCenter().addObserverForName(UIKeyboardDidShowNotification, object: nil, queue: nil, usingBlock: { (notification) -> Void in
            let userInfo = notification.userInfo!
            let keyboardSize = userInfo[UIKeyboardFrameEndUserInfoKey]?.CGRectValue.size
            let contentInsets = UIEdgeInsetsMake(scrollView.contentInset.top, scrollView.contentInset.left, keyboardSize!.height, scrollView.contentInset.right)

            scrollView.setContentInsetAndScrollIndicatorInsets(contentInsets)
            block?(keyboardSize)
        })
    }

    func registerForKeyboardWillHideNotification(scrollView: UIScrollView, usingBlock block: (Void -> Void)? = nil) {
        NSNotificationCenter.defaultCenter().addObserverForName(UIKeyboardWillHideNotification, object: nil, queue: nil, usingBlock: { (notification) -> Void in
            let contentInsets = UIEdgeInsetsMake(scrollView.contentInset.top, scrollView.contentInset.left, 0, scrollView.contentInset.right)
            scrollView.setContentInsetAndScrollIndicatorInsets(contentInsets)
            block?()
        })
    }
}



extension UIScrollView {
    func setContentInsetAndScrollIndicatorInsets(edgeInsets: UIEdgeInsets) {
        self.contentInset = edgeInsets
        self.scrollIndicatorInsets = edgeInsets
    }
}

在viewWillAppear方法中，只需添加如下：

registerForKeyboardWillShowNotification(scrollView)
registerForKeyboardWillHideNotification(scrollView)

每当键盘出现时它都会缩小scrollview的contentInset，并在键盘消失时展开它。

Answer 2

我想我们可以创建包含键盘事件的BaseController，我们必须从它继承viewController并覆盖viewWiillAppear（keyboardWillAppear或keyboardWillDisappear）等键盘方法

需求量的

class BaseController: UIViewController {
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        NotificationCenter.default.addObserver(self, selector: #selector(keyBoardWillShow(notification:)), name: .UIKeyboardWillShow, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyBoardWillHide(notification:)), name: .UIKeyboardWillHide, object: nil)
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillShow, object: nil)
        NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillHide, object: nil)
    }

    //****************************************************
    //MARK: - Keyboard event listener
    //****************************************************

    @objc func keyBoardWillShow(notification: NSNotification) {
       //Override this method
    }

    @objc func keyBoardWillHide(notification: NSNotification) {
        //Override this method
    }
}

如何使用

class ViewController:BaseController {
    override func keyBoardWillHide(notification: NSNotification) {
        // Do something
    }
    override func keyBoardWillShow(notification: NSNotification) {
        // Do something
    }
}

Answer 3

这是Swift 4扩展，其中包含一个需要将Constraint放入其中的方法：

import UIKit

extension UIViewController {

    func bindKeypad(to constraint: NSLayoutConstraint) {
        NotificationCenter.default.addObserver(forName: Notification.Name.UIKeyboardWillShow, object: nil, queue: OperationQueue.main) { [weak self, weak constraint] notification in
            guard let info = notification.userInfo else { return }
            guard let height = (info[UIKeyboardFrameEndUserInfoKey] as? CGRect)?.size.height else { return }
            guard constraint?.constant != height else { return }
            constraint?.constant = height
            self?.view.layoutIfNeeded()

        }

        NotificationCenter.default.addObserver(forName: Notification.Name.UIKeyboardWillHide, object: nil, queue: OperationQueue.main) { [weak self, weak constraint] _ in
            guard constraint?.constant != 0 else { return }
            constraint?.constant = 0
            self?.view.layoutIfNeeded()
        }
    }
}

在你的课堂上有deinit电话：

deinit {
        NotificationCenter.default.removeObserver(self)
    }

在viewDidLoad中使用它调用：

bindKeypad(to: bottomKeypadConstraint)