Question

我已实施keyboardWillShow:和keyboardWillHide:次通知。我正在注册通知，直接触摸UITextField上的屏幕后它们工作正常，但是有问题。在我的viewDidLoad注册通知后，我正在呼叫becomeFirstResponder。键盘弹出但keyboardWillShow:没有被调用（如上所述，只是第一次。从您调用函数注册通知及其实际时间开始，似乎存在延迟注册，我不应该延迟执行becomeFirstResponder）。有什么想法吗？

@objc func keyboardWillShow(_ notification: NSNotification) {
    print("Show")
    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
        var userInfo = notification.userInfo!
        var keyboardFrame:CGRect = (userInfo[UIKeyboardFrameBeginUserInfoKey] as! NSValue).cgRectValue
        keyboardFrame = self.view.convert(keyboardFrame, from: nil)
        var contentInset: UIEdgeInsets = self.tv_main.contentInset
        contentInset.bottom = keyboardSize.height
        self.tv_main.contentInset = contentInset
        let indexpath = IndexPath(row: 0, section: 0)
        self.tv_main.scrollToRow(at: indexpath, at: UITableViewScrollPosition.top, animated: true)
    }
}

@objc func keyboardWillHide(_ notification: NSNotification) {
    print("Hide")
    if let _ = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        let contentInset:UIEdgeInsets = UIEdgeInsets.zero
        self.tv_main.contentInset = contentInset

    }
}

override func viewDidLoad() {
    super.viewDidLoad()
    tv_main.delegate = self
    tv_main.dataSource = self
    tf_search.delegate = self
    NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillShow), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillHide), name: NSNotification.Name.UIKeyboardWillHide, object: nil)
    self.tf_search.becomeFirstResponder()
    if let placeholder = tf_search.placeholder {
        tf_search.attributedPlaceholder = NSAttributedString(string:placeholder, attributes: [NSAttributedStringKey.foregroundColor: UIColor.white])
    }
}

Answer 1

您应该在NotificationCompat.Builder或becomeFirstResponder或viewWillAppear中致电viewDidAppear。

keyboardWillShow在eventFirstResponder之后没有立即调用通知

1 个答案: