Swift3 method of listening to UITextView text changes in iOS development (three methods)

In addition to using the text input box to output UITextField in the project, UITextView is also used frequently. It is inevitable that there will be a need to listen to the number of text in the UITextView text box. The following two common methods are introduced in swift3.

Method 1: Global notification

1. Registration Notification

Register global notifications to listen for UITextView text changes in the appropriate location

//UITextView Two ways to start input by listening to the UITextView//Method 1: Notification(self, selector: #selector(), name: , object: nil)

2. Implement the listening method. The method is named textViewChange

@objc fileprivate func textViewChange() {
XWLog("textViewChange of text :\()")
}

3. In the controller, the ecstasy notification

//Remove Notificationdeinit {
(self)
}

Method 2: Agent

1. Set up a proxy

//1. Set up a proxy = self

2. Comply with the proxy agreement and implement the proxy method

//MARK: - TEXTVIEW DELEGATE
extension ComposeVC : UITextViewDelegate {
func textViewDidChange(_ textView: UITextView) {
if (using: .utf8) > 0 {
//There are texts in the text box that have more than 0 characters. Perform the corresponding operation}else{
//There are text numbers in the text box equal to 0 and perform the corresponding operation}
}
}

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