Protocol协议 按钮点击

#import <Foundation/Foundation.h> @class  Button;  //<>表示实现了某个协议 @protocol ButtonDelegate <NSObject> -(void)onClick:(Button *)btn; @end  @interface Button : NSObject //delegate就是按钮的监听器  <>里面就是指上面的那个协议 @property(nonatomic,retain) id<ButtonDelegate> delegate; -(void)click; @end

#import "Button.h"  @implementation Button  -(void)click{     //如果delegate实现了     if([_delegate respondsToSelector:@selector(onClick:)])     {         //按钮被点击了，就应该通知监听器         [_delegate onClick:self];     }     else     {         NSLog(@"监听器并没有实现onClick:方法");     } }  -(void)dealloc{     [_delegate release];     [super dealloc]; } @end 

#import <Foundation/Foundation.h> #import "Button.h"  @interface MyListener : NSObject<ButtonDelegate>  @end

#import "MyListener.h" #import "Button.h"  @implementation MyListener -(void)onClick:(Button *)btn{     NSLog(@"已经监听到按钮：%@点击了",btn); } @end

#import <Foundation/Foundation.h> #import "Button.h" //一个类要遵守一个协议，要用<>来添加协议名称 @interface ButtonListener : NSObject<ButtonDelegate>  @end

#import "ButtonListener.h"  @implementation ButtonListener -(void)onClick{     NSLog(@"按钮被点击了"); } @end

#import <Foundation/Foundation.h> #import "Button.h" #import "ButtonListener.h" #import "MyListener.h"  int main(int argc, const char * argv[]) {      @autoreleasepool {         //初始化一个按钮         Button *btn=[[[Button alloc] init] autorelease];         //初始化一个按钮监听器         ButtonListener *btnListener=[[[ButtonListener alloc] init] autorelease];         MyListener * mylisten=[[[MyListener alloc] init] autorelease];         //将这个监听器给按钮         btn.delegate=btnListener;         [btn click];         NSLog(@"当前按钮是%@",btn);         btn.delegate=mylisten;         [btn click];     }     return 0; }

2013-08-02 14:47:26.352 Protocol[656:303] 监听器并没有实现onClick:方法

2013-08-02 14:47:26.353 Protocol[656:303] 当前按钮是<Button: 0x100109940>

2013-08-02 14:47:26.354 Protocol[656:303] 已经监听到按钮：<Button: 0x100109940>点击了