[Objective-c 基础 - 3.4] protocol

 1 @protocol MyProtocol
 2 @required
 3 - (void) test1;
 4 
 5 @optional
 6 - (void) test2;
 7 
 8 - (void) test3;
 9 
10 @end

1 #import <Foundation/Foundation.h>
2 #import "MyProtocol.h"
3 
4 @protocol MyProtocol2 <MyProtocol>
5 
6 
7 @end

1 @interface Person : NSObject <MyProtocol]] >
2 
3 @property(nonatomic, strong) id<MyProtocol2> obj;
4 
5 @end

1 int main(int argc, const char * argv[]) {
2     Person *p = [[Person alloc] init];
3     Dog *d = [[Dog alloc] init];
4    
5     p.obj = d; // 警告，Dog没有遵守MyProtocol2协议
6    
7     return 0;
8 }

 1 #import <Foundation/Foundation.h>
 2 
 3 @protocol MyProtocol;
 4 @protocol MyProtocol2;
 5 
 6 @interface Person : NSObject <MyProtocol]] >
 7 
 8 @property(nonatomic, strong) id<MyProtocol2> obj;
 9 
10 @end

 1 #import "Person.h"
 2 #import "MyProtocol.h"
 3 #import "MyProtocol2.h"
 4 
 5 @implementation Person
 6 - (void)test1
 7 {
 8    
 9 }
10 
11 - (void)test3
12 {
13    
14 }
15 
16 @end