键盘出现时，我的UIView不能正常移动。我用来输入文本的UIView中有一个UITextView。如果我选择TextView输入文本，则会出现键盘，但UIView不会第一次移动。如果我点击背景并使键盘消失，然后再次点击TextView，则UIView会正确向上移动。有人知道这里发生了什么吗？
class ChatViewController: UIViewController, CNContactPickerDelegate, UISearchBarDelegate, UITableViewDelegate, UITableViewDataSource, UIToolbarDelegate, UITextFieldDelegate, UITextViewDelegate {
@IBOutlet weak var composeTextView: UITextView!
@IBOutlet weak var composeViewBottomConstraint: NSLayoutConstraint!
override func viewDidLoad() {
super.viewDidLoad()
composeTextView.delegate = self
}
func textViewDidBeginEditing(_ textView: UITextView) {
UIView.animate(withDuration: 0.5){
NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillShow), name: .UIKeyboardWillShow, object: nil)
}
self.view.layoutIfNeeded()
}
@objc func keyboardWillShow(notification: Notification) {
let keyboardSize = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue
let keyboardHeight = keyboardSize?.height
if #available(iOS 11.0, *){
self.composeViewBottomConstraint.constant = keyboardHeight! - view.safeAreaInsets.bottom
}
else {
self.composeViewBottomConstraint.constant = view.safeAreaInsets.bottom
}
self.view.layoutIfNeeded() …