根据键盘的可用性平滑隐藏和显示按钮

Question

所以我在键盘出现时在键盘顶部显示一个按钮，然后在键盘关闭时将其隐藏，但动画流程不够流畅

我想用键盘上下（不阻塞用户界面）

图片：

当键盘出现时，您可以看到键盘仍未完全出现，但我的按钮在这里

当它隐藏时，仍然没有完全消失，但按钮消失了

我的代码：

代码：

viewDidLoad ...... {
        // here we have notification observers for tracking the states of Keyboard
    NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(LaunchScreenViewController.keyboardWillShow(_:)), name: UIKeyboardWillShowNotification, object: nil)

    NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(LaunchScreenViewController.keyboardWillHide(_:)), name: UIKeyboardWillHideNotification, object: nil)

}


    func keyboardWillShow(notification:NSNotification) { // in this function i'm changing the origin (Y) axis of my button os that it can appear on top of my keyboard 
    let userInfo:NSDictionary = notification.userInfo!
    let keyboardFrame:NSValue = userInfo.valueForKey(UIKeyboardFrameEndUserInfoKey) as! NSValue
    let keyboardRectangle = keyboardFrame.CGRectValue()
    UIView.animateWithDuration(0.3) {

        self.nextButtonConstraint.constant  = keyboardRectangle.height
    }
}

func keyboardWillHide(notification:NSNotification) {
    UIView.animateWithDuration(0.5) {

        self.nextButtonConstraint.constant  = -50 // here i'm making my button  out of screen bounds 
    }
}

Answer 1

你应该应用正确的动画：

self.nextButtonConstraint.constant  = keyboardRectangle.height
UIView.animateWithDuration(0.3) {
    <outlet to nextButton>.layoutIfNeeded() // insert correct value in <>
}

并且不要使用 0.3，而是从 UIKeyboardAnimationDurationUserInfoKey 中获取 timeInterval