@protocol myProtocol <NSObject> // 基协议
@required // 声明了必须要实现的，默认情况下都是
@required
- (void)walk;
- (void)speak;
- (void)think; // think在类实现中未实现会警告!!!
@optional
- (void)sing;
- (void)laugh;
@end
协议可以声明一大堆方法，但不能声明成员变量；
两个协议之间不能继承，但协议可以遵守另一个协议；
子类可以遵守父类遵守的协议；
NSObject<myProtocol,allProtocol> * stu = [[Student alloc]init];
等价于
Student *stu = [[Student alloc]init];// 任何类
[stu eat]; // 子类重写了，调用子类的
[stu run]; // 子类没重写，向上找找到父类的方法
student can eat
person can run
Program ended with exit code: 0
Student * stu = [[Student alloc]init];
Student <myProtocol> * student = stu;
NSObject<myProtocol> * student = stu；
id<myProtocol> student = stu;
若报错，就检验出stu没遵守协议
#import "Student.h"
@implementation Student
- (void)exam{
NSLog(@"student can exam.");
}
- (void)eat{
NSLog(@"student can eat");
}
@end
#import <Foundation/Foundation.h>
@protocol allProtocol <NSObject>
- (void)eat;
- (void)run;
@end
#import "Person.h"
@implementation Person
- (void)eat{
NSLog(@"person can eat");
}
- (void)run{
NSLog(@"person can run");
}
@end