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在键盘上方显示UIView无法正常工作

nsnotificationcenter nslayoutconstraint uiview swift ios

Dani iman kazemayni · 技术社区 · 6 年前

我在试着移动 constraintToBottom.constant 的 UIView 我的朋友呢 UITextField 显示后位于键盘上方。我设置了 Notification 观察者,但由于某种原因它不起作用。

override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(_:)), name: UIResponder.keyboardWillShowNotification, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(_:)), name: UIResponder.keyboardWillHideNotification, object: nil)
}

@objc func keyboardWillShow(_ notification: Notification) {
    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
        UIView.animate(withDuration: 0.3, animations: {
            self.constraintToBottom.constant = keyboardSize.height
            print("constant", self.constraintToBottom.constant)
        })
    }
}

当我打印

常数346.0

然而,这个 UIView视图

1 回复 | 直到 6 年前

Shehata Gamal 6 年前

您需要重新布局视图

self.constraintToBottom.constant = -1 * keyboardSize.height
UIView.animate(withDuration: 0.3, animations: {
     self.view.layoutIfNeeded()
     print("constant", self.constraintToBottom.constant)
})

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