// ViewController.h // KVO // // Created by 张国锋 on 15/7/20. // Copyright (c) 2015年 张国锋. All rights reserved. // #import <UIKit/UIKit.h> @interface ViewController : UIViewController @end // // ViewController.m // KVO // // Created by 张国锋 on 15/7/20. // Copyright (c) 2015年 张国锋. All rights reserved. // #import "ViewController.h" #import "StockModel.h" @interface ViewController () { StockModel *_model; UILabel *_label; } @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib. //实例化一个股票，使用setValuesForKeysWithDictionary给所有属性赋值 _model=[StockModel new]; NSDictionary *dic=[NSDictionary dictionaryWithObjects:@[@"A股",@"10.0"] forKeys:@[@"stockName",@"price"]]; [_model setValuesForKeysWithDictionary:dic]; //_model.price=@"22"; /* 1、observer-发送通知的对象 2、keyPath-对象的key,需要观察的属性 3、options－告诉观察者观察的是什么 4、context-被观察者对象传⼊入的context */ [_model addObserver:self forKeyPath:@"price" options:NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOld context:nil]; //label 显示股票的价格 _label=[[UILabel alloc]initWithFrame:CGRectMake(10, 70, 300, 300)]; _label.text=[_model valueForKey:@"price"]; _label.textAlignment=NSTextAlignmentCenter; _label.backgroundColor=[UIColor redColor]; [self.view addSubview:_label]; _label.font=[UIFont systemFontOfSize:50]; UIButton *btn=[[UIButton alloc]initWithFrame:CGRectMake(10, 380, 300, 60)]; [btn addTarget:self action:@selector(btnClick) forControlEvents:UIControlEventTouchUpInside]; [btn setBackgroundColor:[UIColor greenColor]]; [btn setTitle:@"股票涨" forState:UIControlStateNormal]; [btn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal]; [self.view addSubview:btn]; } //change-包含变化之前与变化之后属性值的字典 -(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{ if ([keyPath isEqualToString:@"price"]) { _label.text=[_model valueForKey:@"price"]; NSLog(@"%@",change); } } -(void)btnClick{ NSLog(@"涨"); [_model setValue:@"20.0" forKey:@"price"]; _model.price=@"12"; //_label.text=@"123"; } -(void)dealloc{ [_model removeObserver:self forKeyPath:@"price"]; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } @end
转载于:https://www.cnblogs.com/0515offer/p/4665465.html
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