在Swift中从userInfo获取键盘大小

81

我一直在尝试添加一些代码来在键盘出现时向上移动视图，但是，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步，但是我仍然停留在一条特定的线上。

这是我一直关注的两个教程/问题：

如何使用Swift http://www.ioscreator.com/tutorials/move-view-when-keyboard-appears在键盘出现时向上移动UIViewController的内容

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，我在这条线上出现错误：

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

如果有人能让我知道这行代码应该是什么，那么我应该自己弄清楚其余的代码。

swift  uikeyboard 
— 用户名
source

Answers:

185

您的生产线中存在一些问题：

var keyboardSize = notification.userInfo(valueForKey(UIKeyboardFrameBeginUserInfoKey))
  • notification.userInfo返回可选的字典[NSObject : AnyObject]?，因此在访问它的值之前必须先将其拆开。
  • Objective-CNSDictionary映射到Swift本机字典，因此您必须使用字典下标语法（dict[key]）来访问值。
  • 该值必须强制转换为NSValue以便可以调用CGRectValue它。

所有这些都可以通过可选分配，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：

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：

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代替，keyboardFrameBeginUserInfoKey因为键盘会在较旧的iOS设备上首次显示后更改初始渲染高度。

— 马丁·R
source
@MartinR对不起，我对错误的帖子发表了评论:)对不起
— Lamour
嗨，我正在尝试通过通知获取键盘尺寸，但无法正常工作。我在viewDidload中添加了观察者（也尝试过viewWillAppear）NSNotificationCenter.defaultCenter（）。addObserver（self，选择器：“ keyboardWillShow：”，名称：UIKeyboardWillShowNotification，对象：nil）但未调用该方法。我在真实的设备和模拟器上尝试过。有什么建议吗？非常感谢你。
— theMouse
“一步”答案中有cgRectValue，但应为CGRectValue
— Vladimirs Matusevics
@krotov答案的第一部分是Swift 2，第二部分是Swift3。在这些发行版之间，该属性已重命名。
— Martin R
1
我认为最好在键盘框架发生变化时使用UIKeyboardFrameEndUserInfoKey而不是UIKeyboardFrameBeginUserInfoKey（对于iOS 9或更高版本，可预测性启用或切换到表情符号键盘）
— crcalin 16'7
18

对于更少的代码，请考虑一下THIS

这对我真的很有帮助。您只需要在视图控制器中包括视图约束，并使用添加的两个观察者即可。然后，只需使用以下方法（假设您在这里移动了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() })
  }
} }
— 尼古拉斯
source
1
直到我在其他地方看到它，我才得到这个答案，在我看来tableViewBottomConstraint是Xib的出口。然后很明显，这是完美的答案！（如果您使用的是自动布局）
— Joris van Liempd iDeveloper 2015年
@JorisvanLiempd是的，我正在使用自动布局。很好，对您有帮助。
— 尼古拉斯
似乎动画是免费的，没有动画块。在此答案中，它无论如何都不遵循键盘曲线和持续时间。
— AmitP '16
11

如果您使用情节提要，而不是操纵视图本身，则可以利用自动布局。

（这是“尼古拉斯的答案”的清理版本）

设置通知中心，以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删除：

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)
}

在情节提要板内部，设置底部约束。创建该约束的出口：

在此处输入图片说明

并在显示或隐藏键盘时设置约束的constant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，每当键盘出现或消失时，自动布局都将处理所有事情。

— DudeOnRock
source
4

迅捷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
    }

迅捷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
}
— 巴洛塔克
source
谢谢，对我有很大帮助！
— javimuu
3

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()
— 保罗
source
1

您可以将这一行用作您的行

var keyboardSize:CGSize = userInfo.objectForKey(UIKeyboardFrameBeginUserInfoKey)!.CGRectValue().size
— 阿维纳什
source
3
强制从该字典中解开键盘框架是不安全的。不能在那里。
— Adama
1

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)
}
— 凯文·萨贝
source
1

Swift-从keyboardWillShowNotification获得的键盘高度

您可以使用键盘“将/已显示/隐藏通知”中的数据来将约束或任何其他值增加或缩小到键盘的大小。

具有布局约束

此最少的代码注册以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
    }
}

使用ScrollView

以相同的方式，这会根据键盘的大小来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
  }
}
— 时间史密斯
source
1

细节

  • Xcode版本11.1（11A1027），iOS 13，Swift 5

解

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

在此处输入图片说明

记录

在此处输入图片说明

— 瓦西里·博德纳丘克（Vasily Bodnarchuk）
source
0

斯威夫特3.0

这是一个检索键盘尺寸并使用它来向上动画视图的示例。就我而言，当用户开始输入内容时，我正在向上移动一个包含UITextFields的UIView，以便他们可以填写表单并仍然在底部看到“提交”按钮。

我在要设置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，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()
}
— 流动猫
source
0

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;
   }
— 马塞尔
source
0

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  }```
— 艾贝克·坎卡亚（Aybek Can Kaya）
source
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