An careless wrong pointer.

Try to achieve the following effect:

Enter a character in the box and click the button to change the value of the label box:

ViewController.h

1 #import <UIKit/UIKit.h> 2  3@interface  viewcontroller: Uiviewcontroller  4  5 @property (nonatomic,assign) iboutlet Uitextfield *input1; 6 @property (nonatomic,assign) iboutlet UILabel *output1; 7 8 9 - (ibaction) click1; Ten @end

Viewcontroller.m

1 #import "ViewController.h"2 3 @interfaceViewcontroller ()4 5 @end6 7 @implementationViewcontroller8 9- (void) Viewdidload {Ten [Super Viewdidload]; One     //additional setup after loading the view, typically from a nib. A } -  -- (void) didreceivememorywarning { the [Super didreceivememorywarning]; -     //Dispose of any resources the can be recreated. - } -- (void) click1{ + //nsstring *input1 = _input1.text; - //nsstring *output1 = _output1.text; + //output1 = input1; ANSString *INPUT1 =_input1.text; at_output1.text =input1; -NSString *OUTPUT1 =_output1.text; -      -      -NSLog (@"test:%@,%@", INPUT1,OUTPUT1); -      in      - } to  + @end

Click1 method Inside I was written in the beginning of the commented out 3 lines, after the run normal printing, but the label's text value has not changed. The reason is that "output1 = input1" Only changes the output1 point, so output1 this point to the address that input1 points to, and _output1 's set method is not called. Well, I don't know why I started writing orz like that.

An careless wrong pointer.