从 Swift 中的 userInfo 获取键盘大小

Posted 2023-03-14

【中文标题】从 Swift 中的 userInfo 获取键盘大小

【英文标题】：Getting keyboard size from userInfo in Swift

【发布时间】：2014-08-22 15:54:21

【问题描述】：

我一直在尝试添加一些代码以在键盘出现时向上移动我的视图，但是，我在尝试将 Objective-C 示例转换为 Swift 时遇到了问题。我已经取得了一些进展，但我被困在一个特定的路线上。

这是我一直关注的两个教程/问题：

How to move content of UIViewController upwards as Keypad appears using Swift http://www.ioscreator.com/tutorials/move-view-when-keyboard-appears

这是我目前拥有的代码：

override func viewWillAppear(animated: Bool) 
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillShow:", name: UIKeyboardWillShowNotification, object: nil)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillHide:", name: UIKeyboardWillHideNotification, object: nil)


override func viewWillDisappear(animated: Bool) 
    NSNotificationCenter.defaultCenter().removeObserver(self)


func keyboardWillShow(notification: NSNotification) 
    var keyboardSize = notification.userInfo(valueForKey(UIKeyboardFrameBeginUserInfoKey))
    UIEdgeInsets(top: 0, left: 0, bottom: keyboardSize.height, right: 0)
    let frame = self.budgetEntryView.frame
    frame.origin.y = frame.origin.y - keyboardSize
    self.budgetEntryView.frame = frame


func keyboardWillHide(notification: NSNotification) 
    //

目前，我在这一行遇到错误：

var keyboardSize = notification.userInfo(valueForKey(UIKeyboardFrameBeginUserInfoKey))

如果有人能让我知道这行代码应该是什么，我应该自己弄清楚其余的。

【参考方案1】：

你的线路有一些问题：

var keyboardSize = notification.userInfo(valueForKey(UIKeyboardFrameBeginUserInfoKey))

notification.userInfo 返回一个可选 字典[NSObject : AnyObject]?， 因此必须在访问其值之前对其进行解包。 Objective-C NSDictionary 映射到 Swift 原生字典，所以你必须 使用字典下标语法 (dict[key]) 来访问这些值。 该值必须转换为NSValue，以便您可以调用CGRectValue。

所有这些都可以通过可选赋值、可选链接和可选强制转换的组合来实现：

if let userInfo = notification.userInfo 
   if let keyboardSize = (userInfo[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() 
    let contentInsets = UIEdgeInsets(top: 0, left: 0, bottom: keyboardSize.height, right: 0)
       // ...
    else 
       // no UIKeyboardFrameBeginUserInfoKey entry in userInfo
   
 else 
   // no userInfo dictionary in notification

或一步到位：

if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() 
    let contentInsets = UIEdgeInsets(top: 0, left: 0, bottom: keyboardSize.height, right: 0)
    // ...

Swift 3.0.1 (Xcode 8.1) 更新：

if let userInfo = notification.userInfo 
    if let keyboardSize = userInfo[UIKeyboardFrameBeginUserInfoKey] as? CGRect 
        let contentInsets = UIEdgeInsets(top: 0, left: 0, bottom: keyboardSize.height, right: 0)
        // ...
     else 
        // no UIKeyboardFrameBeginUserInfoKey entry in userInfo
    
 else 
    // no userInfo dictionary in notification

或一步到位：

if let keyboardSize = notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? CGRect 
    let contentInsets = UIEdgeInsets(top: 0, left: 0, bottom: keyboardSize.height, right: 0)
    // ...

Swift 5 (Xcode 11.6) 更新：

 guard let userInfo = notification.userInfo,
              let keyboardSize = userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? CGRect else  return 

我建议使用 keyboardFrameEndUserInfoKey 而不是 keyboardFrameBeginUserInfoKey，因为在旧 iOS 设备上首次显示后，键盘会更改初始渲染高度。

【讨论】：

@MartinR 很抱歉我评论错了帖子:) 抱歉

您好，我正在尝试通过通知获取键盘大小，但无法正常工作。我在 viewDidload 中添加了观察者（也尝试了 viewWillAppear） NSNotificationCenter.defaultCenter().addObserver(self, selector:"keyboardWillShow:", name: UIKeyboardWillShowNotification, object: nil) 但是没有调用该方法。我在真机和模拟器上试了一下。有什么建议吗？非常感谢。

“一步”答案中有 cgRectValue，但应该是 CGRectValue

@krotov 答案的第一部分适用于 Swift 2，第二部分适用于 Swift 3。该属性在这些版本之间已重命名。

我认为在键盘框架发生变化时使用 UIKeyboardFrameEndUserInfoKey 而不是 UIKeyboardFrameBeginUserInfoKey 更好（在 iOS 9 或更高版本中启用预测或切换到表情符号键盘）

【参考方案2】：

对于更少的代码，请考虑查看THIS

这对我真的很有帮助。 您只需在视图控制器中包含视图约束并使用您添加的两个观察者。然后就用下面的方法（这里假设你移动了一个tableView）

func keyboardWillShow(sender: NSNotification) 
        if let userInfo = sender.userInfo 
            if let keyboardHeight = userInfo[UIKeyboardFrameEndUserInfoKey]?.CGRectValue().size.height 
                tableViewBottomConstraint.constant = keyboardHeight
                UIView.animateWithDuration(0.25, animations:  () -> Void in
                    self.view.layoutIfNeeded()
                )
            
        
    

和

func keyboardWillHide(sender: NSNotification) 
if let userInfo = sender.userInfo 
  if let keyboardHeight = userInfo[UIKeyboardFrameEndUserInfoKey]?.CGRectValue().size.height 
    tableViewBottomConstraint.constant = 0.0
    UIView.animateWithDuration(0.25, animations:  () -> Void in self.view.layoutIfNeeded() )
  
 

【讨论】：

直到我在其他地方看到它才得到这个答案，我很清楚 tableViewBottomConstraint 是 Xib 的一个出口。然后很明显这是完美的答案！ （如果您使用的是自动布局）

@JorisvanLiempd 是的，我正在使用自动布局。很好，对你有帮助。

看来动画是免费的，没有动画块。在这个答案中，无论如何都不遵循键盘曲线和持续时间。

【参考方案3】：

如果您使用故事板，而不是操纵视图本身，您可以利用自动布局。

（这是尼古拉斯的答案的清理版本）

设置通知中心，通知您键盘的出现和消失：

override func viewWillAppear(animated: Bool) 
    super.viewWillAppear(animated)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillShow:"), name: UIKeyboardWillShowNotification, object: nil)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillHide:"), name: UIKeyboardWillHideNotification, object: nil)

并确保在不再需要观察者时将其移除：

override func viewWillDisappear(animated: Bool) 
    super.viewWillDisappear(animated)
    NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillShowNotification, object: self.view.window)
    NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillHideNotification, object: self.view.window)

在情节提要中，设置底部约束。创建该约束的出口：

并在键盘显示或隐藏时设置约束的常量属性：

func keyboardWillShow(notification: NSNotification) 
    guard let keyboardHeight = (notification.userInfo! as NSDictionary).objectForKey(UIKeyboardFrameBeginUserInfoKey)?.CGRectValue.size.height else 
        return
    
    nameOfOutlet.constant = keyboardHeight
    view.layoutIfNeeded()


func keyboardWillHide(notification: NSNotification) 
    nameOfOutlet.constant = 0.0
    view.layoutIfNeeded()

现在，无论何时键盘出现或消失，自动布局都会处理所有事情。

【参考方案4】：

斯威夫特 2

func keyboardWasShown(notification:NSNotification) 
        guard let info:[NSObject:AnyObject] = notification.userInfo,
            let keyboardSize:CGSize = (info[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue().size else  return 

        let insets:UIEdgeInsets = UIEdgeInsetsMake(self.scrollView.contentInset.top, 0.0, keyboardSize.height, 0.0)

        self.scrollView.contentInset = insets
        self.scrollView.scrollIndicatorInsets = insets
    

斯威夫特 3

func keyboardWasShown(notification:NSNotification) 
    guard let info:[AnyHashable:Any] = notification.userInfo,
        let keyboardSize:CGSize = (info[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue.size else  return 

    let insets:UIEdgeInsets = UIEdgeInsets(top: self.scrollView.contentInset.top, left: 0.0, bottom: keyboardSize.height, right: 0.0)

    self.scrollView.contentInset = insets
    self.scrollView.scrollIndicatorInsets = insets

【讨论】：

谢谢，对我帮助很大！

【参考方案5】：

这对我有帮助：https://developer.apple.com/library/ios/samplecode/UICatalog/Listings/Swift_UICatalog_TextViewController_swift.html

let userInfo = notification.userInfo!

let animationDuration: NSTimeInterval = (userInfo[UIKeyboardAnimationDurationUserInfoKey] as NSNumber).doubleValue
let keyboardScreenBeginFrame = (userInfo[UIKeyboardFrameBeginUserInfoKey] as NSValue).CGRectValue()
let keyboardScreenEndFrame = (userInfo[UIKeyboardFrameEndUserInfoKey] as NSValue).CGRectValue()

【参考方案6】：

您可以将这一行用作您的行

var keyboardSize:CGSize = userInfo.objectForKey(UIKeyboardFrameBeginUserInfoKey)!.CGRectValue().size

【讨论】：

从该字典中强制展开键盘框架是不安全的。不可能在那里。

【参考方案7】：

Swift 3：更新

override func viewWillAppear(_ animated: Bool) 
    super.viewWillAppear(animated)
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(notification:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(notification:)), name: NSNotification.Name.UIKeyboardWillHide, object: nil)



override func viewWillDisappear(_ animated: Bool) 
    super.viewWillDisappear(animated)
    NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardWillShow, object: self.view.window)
    NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardWillHide, object: self.view.window)

【参考方案8】：

Swift - 来自keyboardWillShowNotification的键盘高度

您可以使用来自键盘 Will/did Show/hide Notifications 的数据将约束或任何其他值增大或缩小到键盘的大小。

带有布局约束

此最小代码注册通知键盘将显示并根据其大小更新约束。

@IBOutlet weak var keyboardConstraint: NSLayoutConstraint!
let keyboardConstraintMargin:CGFloat = 20

override func viewDidLoad() 
    super.viewDidLoad()
    NotificationCenter.default.addObserver(forName: UIResponder.keyboardWillShowNotification, object: nil, queue: nil)  (notification) in
        if let keyboardSize = notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? CGRect 
            self.keyboardConstraint.constant = keyboardSize.height + self.keyboardConstraintMargin
        
    
    NotificationCenter.default.addObserver(forName: UIResponder.keyboardDidHideNotification, object: nil, queue: nil)  (notification) in
        self.keyboardConstraint.constant = self.keyboardConstraintMargin
    

带有滚动视图

以同样的方式，这会根据键盘的大小更新滚动视图的内容插图。

@IBOutlet weak var scrollView: UIScrollView!

override func viewDidLoad() 
  super.viewDidLoad()
  NotificationCenter.default.addObserver(forName: UIResponder.keyboardWillShowNotification, object: nil, queue: nil)  (notification) in
    if let keyboardSize = notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? CGRect 
      let insets = UIEdgeInsets(top: 0, left: 0, bottom: keyboardSize.height, right: 0)
      self.scrollView.contentInset = insets
      self.scrollView.scrollIndicatorInsets = insets
    
  
  NotificationCenter.default.addObserver(forName: UIResponder.keyboardDidHideNotification, object: nil, queue: nil)  (notification) in
    let insets = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
    self.scrollView.contentInset = insets
    self.scrollView.scrollIndicatorInsets = insets
  

【参考方案9】：

详情

Xcode 版本 11.1 (11A1027)、iOS 13、Swift 5

解决方案

import UIKit

protocol KeyboardNotificationsDelegate: class 
    func keyboardWillShow(notification: NSNotification)
    func keyboardWillHide(notification: NSNotification)
    func keyboardDidShow(notification: NSNotification)
    func keyboardDidHide(notification: NSNotification)


extension KeyboardNotificationsDelegate 
    func keyboardWillShow(notification: NSNotification) 
    func keyboardWillHide(notification: NSNotification) 
    func keyboardDidShow(notification: NSNotification) 
    func keyboardDidHide(notification: NSNotification) 


class KeyboardNotifications 

    fileprivate var _isEnabled: Bool
    fileprivate var notifications: [KeyboardNotificationsType]
    fileprivate weak var delegate: KeyboardNotificationsDelegate?

    init(notifications: [KeyboardNotificationsType], delegate: KeyboardNotificationsDelegate) 
        _isEnabled = false
        self.notifications = notifications
        self.delegate = delegate
    

    deinit  if isEnabled  isEnabled = false  


// MARK: - enums

extension KeyboardNotifications 

    enum KeyboardNotificationsType 
        case willShow, willHide, didShow, didHide

        var selector: Selector 
            switch self 
                case .willShow: return #selector(keyboardWillShow(notification:))
                case .willHide: return #selector(keyboardWillHide(notification:))
                case .didShow: return #selector(keyboardDidShow(notification:))
                case .didHide: return #selector(keyboardDidHide(notification:))
            
        

        var notificationName: NSNotification.Name 
            switch self 
                case .willShow: return UIResponder.keyboardWillShowNotification
                case .willHide: return UIResponder.keyboardWillHideNotification
                case .didShow: return UIResponder.keyboardDidShowNotification
                case .didHide: return UIResponder.keyboardDidHideNotification
            
        
    


// MARK: - isEnabled

extension KeyboardNotifications 

    private func addObserver(type: KeyboardNotificationsType) 
        NotificationCenter.default.addObserver(self, selector: type.selector, name: type.notificationName, object: nil)
    

    var isEnabled: Bool 
        set 
            if newValue 
                for notificaton in notifications  addObserver(type: notificaton) 
             else 
                NotificationCenter.default.removeObserver(self)
            
            _isEnabled = newValue
        

        get  return _isEnabled 
    



// MARK: - Notification functions

extension KeyboardNotifications 

    @objc func keyboardWillShow(notification: NSNotification) 
        delegate?.keyboardWillShow(notification: notification)
    

    @objc func keyboardWillHide(notification: NSNotification) 
        delegate?.keyboardWillHide(notification: notification)
    

    @objc func keyboardDidShow(notification: NSNotification) 
        delegate?.keyboardDidShow(notification: notification)
    

    @objc func keyboardDidHide(notification: NSNotification) 
        delegate?.keyboardDidHide(notification: notification)
    

用法

class ViewController: UIViewController 

    private lazy var keyboardNotifications: KeyboardNotifications! = 
        return KeyboardNotifications(notifications: [.willShow, .willHide, .didShow, .didHide], delegate: self)
    ()

    override func viewWillAppear(_ animated: Bool) 
        super.viewWillAppear(animated)
        keyboardNotifications.isEnabled = true
    

    override func viewWillDisappear(_ animated: Bool) 
        super.viewWillDisappear(animated)
        keyboardNotifications.isEnabled = false
    


extension ViewController: KeyboardNotificationsDelegate 

    // If you don't need this func you can remove it
    func keyboardWillShow(notification: NSNotification) 
        print("keyboardWillShow")
        guard   let userInfo = notification.userInfo as? [String: NSObject],
                let keyboardFrame = userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? CGRect else  return 
        print("keyboardFrame: \(keyboardFrame)")
    

    // If you don't need this func you can remove it
    func keyboardWillHide(notification: NSNotification)  print("keyboardWillHide") 

    // If you don't need this func you can remove it
    func keyboardDidShow(notification: NSNotification)  print("keyboardDidShow") 

    // If you don't need this func you can remove it
    func keyboardDidHide(notification: NSNotification)  print("keyboardDidHide") 

完整样本

import UIKit

class ViewController: UIViewController 

    private lazy var keyboardNotifications: KeyboardNotifications! = 
        return KeyboardNotifications(notifications: [.willShow, .willHide, .didShow, .didHide], delegate: self)
    ()

    override func viewDidLoad() 
        super.viewDidLoad()

        let textField = UITextField(frame: CGRect(x: 40, y: 40, width: 200, height: 30))
        textField.borderStyle = .roundedRect
        view.addSubview(textField)

        let gesture = UITapGestureRecognizer(target: view, action: #selector(UIView.endEditing(_:)))
        view.addGestureRecognizer(gesture)
    

    override func viewWillAppear(_ animated: Bool) 
        super.viewWillAppear(animated)
        keyboardNotifications.isEnabled = true
    

    override func viewWillDisappear(_ animated: Bool) 
        super.viewWillDisappear(animated)
        keyboardNotifications.isEnabled = false
    


 extension ViewController: KeyboardNotificationsDelegate 

    // If you don't need this func you can remove it
    func keyboardWillShow(notification: NSNotification) 
        print("keyboardWillShow")
        guard   let userInfo = notification.userInfo as? [String: NSObject],
                let keyboardFrame = userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? CGRect else  return 
        print("keyboardFrame: \(keyboardFrame)")
    

    // If you don't need this func you can remove it
    func keyboardWillHide(notification: NSNotification)  print("keyboardWillHide") 

    // If you don't need this func you can remove it
    func keyboardDidShow(notification: NSNotification)  print("keyboardDidShow") 

    // If you don't need this func you can remove it
    func keyboardDidHide(notification: NSNotification)  print("keyboardDidHide") 

结果

日志

【参考方案10】：

Swift 3.0

下面是一个检索键盘大小并使用它为向上的视图设置动画的示例。在我的情况下，当用户开始输入时，我将包含我的 UITextFields 的 UIView 向上移动，以便他们可以完成表单并仍然在底部看到提交按钮。

我在想要动画的视图的底部空间约束中添加了一个出口，并将其命名为myViewsBottomSpaceConstraint：

@IBOutlet weak var myViewsBottomSpaceConstraint: NSLayoutConstraint!

然后我将以下代码添加到我的 swift 类中：

override func viewWillAppear(_ animated: Bool) 
    super.viewWillAppear(animated)
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(notification:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(notification:)), name: NSNotification.Name.UIKeyboardWillHide, object: nil)



override func viewWillDisappear(_ animated: Bool) 
    super.viewWillDisappear(animated)
    NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardWillShow, object: self.view.window)
    NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardWillHide, object: self.view.window)


func keyboardWillShow(notification: NSNotification) 

    let userInfo = notification.userInfo as! [String: NSObject] as NSDictionary
    let keyboardFrame = userInfo.value(forKey: UIKeyboardFrameEndUserInfoKey) as! CGRect
    let keyboardHeight = keyboardFrame.height
    myViewsBottomSpaceConstraint.constant = keyboardHeight
    view.layoutIfNeeded()


func keyboardWillHide(notification: NSNotification) 
    myViewsBottomSpaceConstraint.constant = 0.0
    view.layoutIfNeeded()

【参考方案11】：

对于 xamarin，您可以使用 c#6

private void KeyboardWillChangeFrame(NSNotification notification)

        var keyboardSize = notification.UserInfo.ValueForKey(UIKeyboard.FrameEndUserInfoKey) as NSValue;
        if (keyboardSize != null)
        
            var rect= keyboardSize.CGRectValue;
            //do your stuff here
        

c#7

  private void KeyboardWillChangeFrame(NSNotification notification)
   
       if (!(notification.UserInfo.ValueForKey(UIKeyboard.FrameEndUserInfoKey) is NSValue keyboardSize)) return;
       var rect= keyboardSize.CGRectValue;
   

【参考方案12】：

在 Swift 4.2 中，您可以使用 UIResponder.keyboardFrameEndUserInfoKey

guard let userInfo = notification.userInfo , let keyboardFrame:CGRect = userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? CGRect  else  return  ```