[非凡程序员]观察者模式

摘要: 非凡程序员，感谢 黄杨超ios指导，总结：毕绒超学习笔记

#import <Foundation/Foundation.h>
#import "Student.h"
#import "Goods.h"
int main(int argc, const char * argv[]) {
@autoreleasepool {
Student *stu=[[Student alloc]init];
stu.name=@"Student_one";

//----------- 通知 --------------
//通知步骤： 注册/接收 --> 通知 --> 移除

//注册（某个对象 student） + 接收的方法(@select(自定义方法名))
//注意：每当写入注册对象，请在注册对象里写上接收方法。
//参数说明：addObserver: 观察者 selector:@select(接收方法)
//接收方法最好加冒号，为了参数传参数。name: 通知名称 object：通知发送人 可为nil
[[NSNotificationCenter defaultCenter] addObserver:stu selector:@selector(backChangeMessage:) name:@"notificationStudent" object:nil];
//通知方法 一般为发送通知消息
//注意：通知名称必须为已注册的通知名称，发送的通知可为任意对象类型
//参数说明：postNotificationName: 通知名称 objects: 被发送消息
[[NSNotificationCenter defaultCenter] postNotificationName:@"notificationStudent" object:stu];

//----- 拉模型 可用delegate实现 -----
//拉模型： 由商品给出更改消息，仅仅是消息，由Person主动去拉取Goods信息
//Goods -> setPrice 通过更改price值，回调通知消息给Person类， Person主动去拉去值

Goods *good=[[Goods alloc]init];
good.price=12;

Student *xiaoMing=[[Student alloc]init];
xiaoMing.name=@"XiaoMing";

xiaoMing.goods=good;
good.stu=xiaoMing;

[[NSNotificationCenter defaultCenter] addObserver:xiaoMing selector:@selector(backMessage:) name:@"goodsNotification" object:nil];
[[NSNotificationCenter defaultCenter] postNotificationName:@"goodsNotification" object:good];
good.price=22;
}
return 0;
}

@protocol myProtocol <NSObject>
@optional

@property(nonatomic,assign)float price;

-(void)changeMethod;
@end

#import <Foundation/Foundation.h>
#import "goodsProtocol.h"
#import "Student.h"
@interface Goods : NSObject<myProtocol>
@property(nonatomic,strong)id<myProtocol> stu;

@end

@implementation Goods
@synthesize price=_price;
-(void)setPrice:(float)price{
_price=price;
[_stu changeMethod];
}

@end

#import <Foundation/Foundation.h>
#import "goodsProtocol.h"
@class Goods;
@interface Student : NSObject<myProtocol>
@property(nonatomic,strong)NSString *name;
@property(nonatomic,weak)id<myProtocol> goods;

-(void)backChangeMessage:(NSNotification *)notifacation;
-(void)backMessage:(NSNotification *)goodsNotification;

@end

#import "Student.h"

@implementation Student

-(void)changeMethod{
NSLog(@"changeMethod ...");
NSLog(@"%f",_goods.price);
}

-(void)backChangeMessage:(NSNotification *)notifacation{
Student *student=notifacation.object;
NSLog(@"name:%@",student.name);

}

-(void)backMessage:(NSNotification *)goodsNotification{
NSLog(@"%@",goodsNotification.object);
// _goods=goodsNotification.object;
// [_goods ]
}

-(void)dealloc{
//移除 防止内存泄漏
//方法说明： removeObserver: 观察者 name: 通知名称 object 发送人 该方法为移除观察者的消息通知
[[NSNotificationCenter defaultCenter] removeObserver:self name:@"notificationStudent" object:nil];
//方法说明： removeObserver: 观察者 该方法为移除观察者对象
[[NSNotificationCenter defaultCenter] removeObserver:self];

[[NSNotificationCenter defaultCenter] removeObserver:self name:@"goodsNotification" object:nil];
//方法说明： removeObserver: 观察者 该方法为移除观察者对象
[[NSNotificationCenter defaultCenter] removeObserver:_goods];

}

@end