OC-KVO的应用

main.m

#import <Foundation/Foundation.h>

#import "Person.h"

#import "Ibokan.h"

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

{

    @autoreleasepool

    {

        //(1)KVO测试

        

        Ibokan *ib=[Ibokannew];

        NSLog(@"%@",ib.frontDesk.someone);

        

        //改变属性值,会自动调用observeValueForKeyPath

     //   [ib comein:@"daleng"];

        

      

    }

    return0;

}

Person.h

#import <Foundation/Foundation.h>

@interface Person : NSObject

@property (nonatomic,copy)NSString *someone;

@end

Ibok.h

#import <Foundation/Foundation.h>

#import "Person.h"

@interface Ibokan : NSObject

//前台妹妹

@property (nonatomic,strong)Person *frontDesk;

//模拟进来一个人,改变所记录的名字

-(void)comein:(NSString *)name;

@end

Ibok.m

#import "Ibok.h"

@implementation Ibokan

- (instancetype)init

{

    self = [superinit];

    if (self) {

        

        self.frontDesk= [Person new];

        self.frontDesk.someone=@"yang";

        //1.注册订阅者

        [self.frontDeskaddObserver:selfforKeyPath:@"someone"options:NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOldcontext:nil];

    }

    returnself;

}

//2.处理属性改变

//一旦.someone改变,此方法就是调用

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context

{

    NSLog(@"==================");

    NSLog(@"%@",change);

    NSLog(@"新的值:%@",change[@"new"]);

    NSLog(@"旧的值:%@",change[@"old"]);

    if ([change[@"new"]isEqualToString:@"ladeng"]) {

        

        NSLog(@"校长出来迎接");

    }

    

    

}

-(void)comein:(NSString *)name

{

    self.frontDesk.someone=name;

}

-(void)dealloc

{

    [self.frontDeskremoveObserver:selfforKeyPath:@"someone"];

}

@end