@protocol Study; int main(int argc, const char * argv[]) { @autoreleasepool { Student *stu = [[[Student alloc] init] autorelease]; // 注意:OC是弱语法的,对类型要求不严格 // NSString *stu = [[[Student alloc] init] autorelease]; // [stu stringByAbbreviatingWithTildeInPath]; // conformsToProtocol:判断是否遵照了某个协议
if ([stu conformsToProtocol:@protocol(Study)]) { NSLog(@"Student遵照了Study这个协议"); } // respondsToSelector:判断是否实现了某个方法
if ( ![stu respondsToSelector:@selector(test)] ) { NSLog(@"Student没有实现test这个方法"); } } return 0; }
#import <Foundation/Foundation.h>
@protocol Study <NSObject>
// 默认就是@required
- (void)test3; // @required表示必须实现的方法 // 虽然字面上说是必须实现,可是编译器并不强求某个类进行实现
@required - (void)test; - (void)test1; // @optional表示可选(可实现\也可不实现)
@optional - (void)test2; @end
#import <Foundation/Foundation.h>
@class Button; // <>表明实现某个协议
@protocol ButtonDelegate <NSObject>
- (void)onClick:(Button *)btn; @end
@interface Button : NSObject // delegate就是按钮的监听器
@property (nonatomic, retain) id<ButtonDelegate> delegate; // 点击按钮
- (void)click; @end
#import "Button.h"
@implementation Button - (void)dealloc { [_delegate release]; [super dealloc]; } - (void)click { // 若是_delegate实现了onClick:这个方法
if ( [_delegate respondsToSelector:@selector(onClick:)] ) { // 按钮被点击了,就应该通知监听器.而且告诉监听器哪一个按钮被点击了
[_delegate onClick:self]; } else { NSLog(@"监听器并无实现onClick:方法"); } } @end
调用ui
#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 *button = [[[Button alloc] init] autorelease]; // 初始化一个按钮的监听器 // ButtonListener *listener = [[[ButtonListener alloc] init] autorelease];
MyListener *listener = [[[MyListener alloc] init] autorelease]; // 设置按钮的监听器
button.delegate = listener; NSLog(@"button:%@", button); // 点击按钮
[button click]; Button *button2 = [[[Button alloc] init] autorelease]; button2.delegate = listener; NSLog(@"button2:%@", button2); // 点击button2
[button2 click]; } return 0; }