iOS Listening TextField content changes

Source: Internet
Author: User

This article is only for the help of many people. Suitable for beginners. here I introduce 3 kinds of methods to monitor Uitextfield . And at last wrote a small demo to provide reference.
-------Please do not struggle with the name of the small series of rules, all only for common learning, common progress. @property (Weak, nonatomic) Iboutlet Uitextfield *userid; @property (Weak, nonatomic) Iboutlet Uitextfield *password; @property (Weak, nonatomic) Iboutlet UIButton *loginbut; several ways to listen to the contents of a text box: (for Login-to-search) 1. Agent (can only listen to the text box that has the proxy set not set the proxy text box does not listen) <UITextFieldDelegate>   _userid.delegate=self (set proxy)     //Whether you can edit Yes to no -(BOOL) textfieldshouldbeginediting: (Uitextfield *) textfield{ return YES; } //Start editing when the call -(void) textfielddidbeginediting: (Uitextfield *) textfield{ NSLog (@ "Start editing"); }   //Whether to allow end edits (this is called first when the user ends a text box) //If no means, this text box is always in the edit state (also called the first responder), even if you click another text box, it is not any effect -(BOOL) textfieldshouldendediting: (Uitextfield *) textfield{ return YES; } //End of Edit call -(void) textfielddidendediting: (Uitextfield *) textfield{ NSLog (@ "end edit"); }   //Whether the user is allowed to enter files //The user will be called once each time a character is entered. Then judge the non-display in the text box -(BOOL) TextField: (Uitextfield *) TextField Shouldchangecharactersinrange: (nsrange) range replacementstring: ( NSString *) string{ //Print nsstring *text=[nsstring stringwithformat:@ "%@%@", textfield.text,string]; NSLog (@ "------%@", text); return YES; } //Allows you to clear what is entered in the current text box -(BOOL) Textfieldshouldclear: (Uitextfield *) textfield{ return YES; }   2. Notifications (all text boxes can be monitored)    /* uitextfieldtextdidchangenotification//Notification of Change of text box Object:_userid represents the _userid text box Object:nil represents all text boxes      */ [Nsnotificationcenter defaultcenter]addobserver:self selector: @selector (textchange) Name: Uitextfieldtextdidchangenotification Object:nil];   -(void) textchange{ NSLog (@ "-----change-----"); }  The notification to be created is to be removed when the current pair is being destroyed: (otherwise an error may occur, bad memory access) -(void) dealloc{ [[Nsnotificationcenter Defaultcenter] removeobserver:self]; }   3. Listener (AddTarget) ()   /*Events : I'm going to lose this method when I'm in the event of something. uicontroleventeditingchanged: When the text box is edited      */   [_userid addtarget:self Action: @selector (TextChange) forcontrolevents:uicontroleventeditingchanged];     [_password addtarget:self Action: @selector (TextChange) forcontrolevents:uicontroleventeditingchanged];    } //I set the 2 text box listener trigger method to TextChange to determine if the login button can be clicked //Only 2 text boxes have values to click (here according to your needs) -(void) textchange{ if (_userid.text.length && _password.text.length) { _loginbut.enabled=yes; }else{ _loginbut.enabled=no;     } //This judgment can be optimized to one line: _loginbut.enabled=_userid.text.length && _password.text.length;   NSLog (@ "Gaibia-----"); }     Demo notifications are used with the agent: If you have 5 text boxes or listen to multiple simultaneous listeners, I want to print out which text box (first responder) is in the editor and what the content is: Code:

  There is no need to drag the line (your storyboard to be associated with your Viewcontroller)   #import "ViewController.h"   @interface Viewcontroller () <UITextFieldDelegate>   //@property (nonatomic, strong) Nsarray *textfieldall;//store all TextField   @property (nonatomic, strong) Uitextfield *newtext;//get Uitextfield in edit state @end   @implementation Viewcontroller         -(void) Viewdidload { //Create an array store TextField Nsmutablearray *FIELDSM = [Nsmutablearray array];     //No tow line //This code is to get all the controls on the view, including the Label,textfield; Nsarray *childarray=self.view.subviews;   //Loop through all the controls For (UIView *child in Childarray) {         //Find out all the Textfieldall if ([Child Iskindofclass:[uitextfield class]]) { //Type conversion Uitextfield *textfield= (Uitextfield *) child;   //Set up proxy textfield.delegate=self;             //[FIELDSM Addobject:textfield];           }     } //_TEXTFIELDALL=FIELDSM;     //Create a notification: Listen to every TextField [[Nsnotificationcenter defaultcenter] addobserver:self selector: @selector (textchange) Name: Uitextfieldtextdidchangenotification Object:nil]; }   -(void) textchange{ //print TextField and tag in edit state NSLog (@ "%@-%ld", _newtext.text, (long) _newtext.tag);   }   -(void) textfielddidbeginediting: (Uitextfield *) textfield{     _newtext=[[uitextfield Alloc]init]; _newtext=textfield;     }   @end   last Run effect and print ——————————————————  

iOS Listening TextField content changes

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