oc的协议(protocol)

Button.h文件

#import <Foundation/Foundation.h>

@protocol  Buttondeleget

-(void) onClick;

@end

@interface Button : NSObject

@property(nonatomic,retain)id<Buttondeleget> deleaget;

-(void)click;

@end

Button.m文件
#import "Button.h"

@implementation Button

-(void)click{

    [_deleaget onClick];
}

@end

ButtonListener.h文件
#import <Foundation/Foundation.h>
#import "Button.h"

@interface ButtonListener : NSObject<Buttondeleget>

@end

ButtonListener.m文件
#import "ButtonListener.h"

@implementation ButtonListener
-(void)onClick{
    NSLog(@"这个按钮被点击了");
}
@end

main.m文件
#import <Foundation/Foundation.h>
#import "Button.h"
#import "ButtonListener.h"

int main(int argc, const char * argv[])
{

    @autoreleasepool {
        Button *button=[[Button alloc]init];
        ButtonListener *buttonlistener=[[ButtonListener alloc]init];
        button.deleaget=buttonlistener;
        [button click];
    }
    return 0;
}