我有一个 TextView (textView)和一个按钮(sendButton)。 按钮的底部约束是对 View 底部的约束。 textView 成为 viewDidAppear 中的第一响应者。 因此,当我展示 Controller 时,键盘会升起,按钮也会随之动画。
代码如下:
override func viewDidLoad() {
super.viewDidLoad()
setupSendButton()
dismissKeyboard()
}
override func viewDidAppear(_ animated: Bool) {
textView.becomeFirstResponder()
}
func setupSendButton() {
self.view.addSubview(sendButton)
sendButton.leadingAnchor.constraint(equalTo: self.view.leadingAnchor).isActive = true
sendButton.trailingAnchor.constraint(equalTo: self.view.trailingAnchor).isActive = true
sendButton.heightAnchor.constraint(equalToConstant: 60).isActive = true
sendButton.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true
sendButton.translatesAutoresizingMaskIntoConstraints = false
}
// TextView Delegate Method
func textViewDidBeginEditing(_ textView: UITextView) {
// Animation begins after textView did begin editing
animateSendButton(bottomConstraint: -216)
}
此时一切正常。
我的问题是,当我关闭键盘并结束编辑时,我想动画回来,以便按钮的底部约束再次成为 View 的底部约束。
但这是行不通的。
// TextView Delegate Method
func textViewDidEndEditing(_ textView: UITextView) {
// Animation begins after textView did end editing (it doesn't)
animateSendButton(bottomConstraint: 0)
}
// function to dismiss keyboard and end editing
func dismissKeyboard() {
let touch = UITapGestureRecognizer(target: self, action: #selector(tapGesture))
self.view.addGestureRecognizer(touch)
}
@objc func tapGesture(gesture: UITapGestureRecognizer){
// Ends editing and dismisses keyboard
self.view.endEditing(true)
}
动画按钮功能:animateSendButton(bottomConstraint: CGFloat)
func animateSendButton(bottomConstraint: CGFloat) {
sendButton.bottomAnchor.constraint(equalTo: self.view.bottomAnchor, constant: bottomConstraint).isActive = true
UIView.animate(withDuration: 0.55, delay: 0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: .curveEaseIn, animations: {
self.view.layoutIfNeeded()
}, completion: nil)
}
最佳答案
在添加其他底部约束之前,您必须删除先前的底部约束
或更改
var bottomCon:NSLayoutConstraint!
//////
func setupSendButton() {
self.view.addSubview(sendButton)
sendButton.leadingAnchor.constraint(equalTo: self.view.leadingAnchor).isActive = true
sendButton.trailingAnchor.constraint(equalTo: self.view.trailingAnchor).isActive = true
sendButton.heightAnchor.constraint(equalToConstant: 60).isActive = true
self.bottomCon = sendButton.bottomAnchor.constraint(equalTo: self.view.bottomAnchor)
self.bottomCon.active= true
sendButton.translatesAutoresizingMaskIntoConstraints = false
}
func animateSendButton(bottomConstraint: CGFloat) {
self.bottomCon.constant = bottomConstraint
UIView.animate(withDuration: 0.55, delay: 0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: .curveEaseIn, animations: {
self.view.layoutIfNeeded()
}, completion: nil)
}
关于ios - UIButton 的返回动画不起作用,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/48356647/