blocks|key|354894|text|您可以像这样添加一个类成员NSString+*changeTemp，然后|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|354895|changetemp+=+textfield;

if(+change+temp+!=+textfild+){
++++changetemp=textfild;
++++NSLog(@"+text+is+changed"
}+else+{+
++++NSLog(@"+text+isn't+changed"):
}|code-block|syntax|javascript|354896|entityMap^0|D|K|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

You can add a class member like this <code>NSString *changeTemp</code>,then 

<pre><code>changetemp = textfield;

if( change temp != textfild ){
 changetemp=textfild;
 NSLog(@" text is changed"
} else { 
 NSLog(@" text isn't changed"):
}
</code></pre>

blocks|key|137073|text|您可以创建一个变量来存储原始字符串，然后向通知中心注册以接收UITextFieldTextDidChangeNotification事件：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|137074|[[NSNotificationCenter+defaultCenter]+addObserver:self+selector:@selector(updateButton:)+name:UITextFieldTextDidChangeNotification+object:nil];|code-block|syntax|javascript|137075|然后，创建接收通知的方法，并将文本字段的当前值与原始值进行比较|137076|-(void)+updateButton:(NSNotification+*)notification+{
+++++++self.myButton.enabled+=+![self.myTextField.text+isEqualToString:originalString];
}|137077|当视图控制器被释放时，不要忘记取消注册通知。|137078|[[NSNotificationCenter+defaultCenter]+removeObserver:self+name:UITextFieldTextDidChangeNotification+object:nil];|137079|entityMap^0|U|10|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|Y|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|Z|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|10|8|@]|D|@]|E|$]]|$1|Q|3|R|5|H|7|11|8|@]|D|@]|E|$I|J]]|$1|S|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|T|$]]

You could create a variable to store the original string, then register with the notification center to receive <code>UITextFieldTextDidChangeNotification</code> event:

<pre><code>[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(updateButton:) name:UITextFieldTextDidChangeNotification object:nil];
</code></pre>

Then, create a method to receive the notification, and compare the current value of the text field with the original value

<pre><code>-(void) updateButton:(NSNotification *)notification {
 self.myButton.enabled = ![self.myTextField.text isEqualToString:originalString];
}
</code></pre>

Don't forget to de-register the notification when the view controller is deallocated.

<pre><code>[[NSNotificationCenter defaultCenter] removeObserver:self name:UITextFieldTextDidChangeNotification object:nil];
</code></pre>

blocks|key|137135|text|为此，首先您需要为您的文本字段分配委托引用。并且delgate最好是作为视图的文件所有者的view控制器。它是这样的|type|unstyled|depth|inlineStyleRanges|entityRanges|data|137136|myTextField.delegate+=+myViewControllerReferenceVariable|code-block|syntax|javascript|137137|在您的viewController界面中，告诉您将通过以下方式实现UITextFieldDelegate|137138|@interface+MyViewController:UIViewController<UITextFieldDelegate>|137139|，并且在视图控制器实现重写中|137140|-+(BOOL)textField:(UITextField+*)textField+shouldChangeCharactersInRange:(NSRange)range+replacementString:(NSString+*)string|137141|因此，代码将如下所示|137142|-+(BOOL)textField:(UITextField+*)textField+shouldChangeCharactersInRange:(NSRange)range+replacementString:(NSString+*)string
+++++{
++++++++text+=+[textfield.text+stringByReplacingCharactersInRange:range+withString:string];
++++++++if+(textfield+==+refToTextFieldYouWantToCheck)+{
++++++++++++if+(+!+[textToCheck+isEqualToString:text]+)+{
+++++++++++++++[theButtonRef+setEnabled:YES];
++++++++++++}+
+++++++++}
+++++++++++return+YES;+//If+you+don't+your+textfield+won't+get+any+text+in+it
++++++}|137143|你也可以订阅通知，这是一种混乱的IMHO你可以找到如何做到这一点here。|offset|length|137144|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/7010547/uitextfield-text-change-event^0|0|0|0|0|0|0|0|0|W|4|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|15|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|16|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|17|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|18|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|19|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|1A|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|1B|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|1C|8|@]|9|@$U|1D|V|1E|1|1F]]|A|$]]|$1|W|3|-4|5|6|7|1G|8|@]|9|@]|A|$]]]|X|$Y|$5|Z|10|11|A|$12|13]]]]

For that, first you need to have your textfield have it delegate reference assigned. And the delgate, should preferably be, the vew controller which is the files owner of the view.
Which goes like

<pre><code>myTextField.delegate = myViewControllerReferenceVariable
</code></pre>

And in your viewController interface, tell you will be implementing UITextFieldDelegate by

<pre><code>@interface MyViewController:UIViewController&lt;UITextFieldDelegate&gt;
</code></pre>

And in your view controller implementation override 

<pre><code>- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
</code></pre>

So the code will look like

<pre><code>- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
 {
 text = [textfield.text stringByReplacingCharactersInRange:range withString:string];
 if (textfield == refToTextFieldYouWantToCheck) {
 if ( ! [textToCheck isEqualToString:text] ) {
 [theButtonRef setEnabled:YES];
 } 
 }
 return YES; //If you don't your textfield won't get any text in it
 }
</code></pre>

You can also subscribe to notification which is sort of messy IMHO
You can find how to do it <a href="https://stackoverflow.com/questions/7010547/uitextfield-text-change-event">here</a>.

blocks|key|137190|text|Swift+3.0|type|unstyled|depth|inlineStyleRanges|entityRanges|data|137191|流程1|137192|创建UITextfiled的IBOutlet并将目标添加到文本字段。|137193|+m_lblTxt.addTarget(self,+action:+#selector(self.textFieldDidChange),+for:+UIControlEvents.editingChanged)

+func+textFieldDidChange(textField:UITextField)
+{
+++++NSLog(textField.text!)
+}|code-block|syntax|javascript|137194|流程2|137195|+m_lblTxt.delegate+=+self

+//MARK:+-+TextField+Delegates
+func+textField(_+textField:+UITextField,+shouldChangeCharactersIn+range:+NSRange,+replacementString+string:+String)+->+Bool+
+{
++++++print(textField.text!)
++++++return+true
+}|137196|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|S|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|T|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|H|7|V|8|@]|9|@]|A|$I|J]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Swift 3.0

Process 1

Create IBOutlet of UITextfiled and Add Target to text field.

<pre><code> m_lblTxt.addTarget(self, action: #selector(self.textFieldDidChange), for: UIControlEvents.editingChanged)

 func textFieldDidChange(textField:UITextField)
 {
 NSLog(textField.text!)
 }
</code></pre>

Process 2 

<pre><code> m_lblTxt.delegate = self

 //MARK: - TextField Delegates
 func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -&gt; Bool 
 {
 print(textField.text!)
 return true
 }
</code></pre>

blocks|key|355113|text|这可以在UITextField的Editing+Changed事件上的接口生成器中完成。将其拖到您的代码中，然后创建一个IBAction。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|355114|例如：|355115|@IBAction+func+textFieldChanged(_+sender:+UITextField)+{
++print(sender.text)
}|code-block|syntax|javascript|355116|此事件与此处的其他答案中所述的事件相同，因为.text属性包含触发时更新的文本输入。这有助于清理代码杂乱，因为不必以编程方式将事件添加到视图中的每个UITextField。|355117|entityMap^0|4|B|G|F|1O|8|0|0|0|M|5|22|B|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|Y|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|Z|8|@$9|10|A|11|B|C]|$9|12|A|13|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|P|$]]

This can be accomplished in Interface Builder on the <code>Editing Changed</code> event of <code>UITextField</code>. Drag from it to your code and create an <code>IBAction</code>.

For example:

<pre><code>@IBAction func textFieldChanged(_ sender: UITextField) {
 print(sender.text)
}
</code></pre>

This event is the same as described in other answers here in that the <code>.text</code> property contains the updated text input when it gets triggered. This can help clean up code clutter by not having to programmatically add the event to every <code>UITextField</code> in the view.

I would like to be able to detect if some text is changed in a <code>UITextField</code> so that I can then enable a <code>UIButton</code> to save the changes.

Detecting a change to text in UITextfield

Swift

我希望能够检测到UITextField中的某些文本是否发生了更改，这样我就可以启用UIButton来保存更改。

问检测UITextfield中的文本更改
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