oc Delegate

把内部的状态通知给外界，我们可以制定一个变量，然后这个变量从外界来指定，之后我们可以通过变量去通知给外界有什么发生了。

按照上文讲的到新建一个protocol,名字为IPeople

#import <Foundation/Foundation.h>

//oc里面的协议相当于java里面的接口
@protocol IPeople <NSObject>

-(int)getAge;
-(void)setAge:(int)age;

-(NSString*)getName;

@end

新建一个类文件

Man.h

#import <Foundation/Foundation.h>
#import "IPeople.h"
#import "ManDelegate.h"

@interface Man : NSObject<IPeople> //可以写入多个接口，以逗号（，）隔开
{
    int _age;
}
-(id)init;

-(int)getAge;
-(void)setAge:(int)age;

-(NSString*)getName;

@property id<ManDelegate> delegate;

@end

Man.m

#import "Man.h"

@implementation Man:NSObject

- (instancetype)init
{
    self = [super init];//相当于java里面的this
    if (self) {
        self.delegate=nil;
    }
    return self;
}

-(int)getAge{
    return _age;
}

-(void)setAge:(int)age{
    if(age!=_age){ //当age值发生变化时代理执行类
        if(self.delegate){
            [self.delegate onAgeChange:age];
        }
    }
    _age=age;
}

-(NSString*)getName{
    return @"Netcorner";
}

@end

新建一个delegate类协议

#import <Foundation/Foundation.h>

@protocol ManDelegate <NSObject>
-(void)onAgeChange:(int)age;
@end

主程序为：

#import <UIKit/UIKit.h>
#import "AppDelegate.h"
#import "Man.h"
#import "ManDelegate.h"
//实现delegate协议的类
@interface ManListener : NSObject<ManDelegate>
-(void)onAgeChange:(int)age;
@end

@implementation ManListener

-(void)onAgeChange:(int)age{
    NSLog(@"Age Changed,Current age is %d",age);
}
@end

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

    Man *m=[[Man alloc]init ];
    [m setDelegate:[[ManListener alloc]init]];
    [m setAge:];

}