KVO

最新推荐文章于 2025-06-25 16:46:38 发布

金牌博客

最新推荐文章于 2025-06-25 16:46:38 发布

阅读量243

点赞数

CC 4.0 BY-SA版权

分类专栏： UI 文章标签： KVO

本文链接：https://blog.youkuaiyun.com/qxwwxq/article/details/51159537

UI 专栏收录该内容

11 篇文章

订阅专栏

本文介绍了一款iOS游戏中如何使用KVO(key-value observing)来观察角色血量的变化，并通过定时器模拟血量减少的过程，同时展示了如何添加和移除观察者。

#import "ViewController.h"
#import "Hero.h"
@interface ViewController ()
@property(nonatomic,strong)Hero *hero;
@property(nonatomic,strong)UIView *view1;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    //KVO 键值观察(来观察对象的属性是否发生了变化)
    _hero = [[Hero alloc] init];
    _hero.blood = 300;
    [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(bloodLess) userInfo:nil repeats:YES];
    //添加观察者观察英雄的血量
    [_hero addObserver:self forKeyPath:@"blood" options:NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOld context:nil];


}
//一旦血量发生变化 就会触发这个方法
-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context
{
    NSString *newBlood = [change objectForKey:@"new"];
    if ([newBlood integerValue] <= 50) {
        _hero.blood = 300;
    }
}
//移除监听
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    //移除监听观察
    [_hero removeObserver:self forKeyPath:@"blood"];
}
-(void)bloodLess
{
    [_view1 removeFromSuperview];
    _view1 = [[UIView alloc] initWithFrame:CGRectMake(10, 100, _hero.blood, 50)];
    _view1.backgroundColor = [UIColor redColor];
    [self.view addSubview:_view1];
    _hero.blood -= 50;
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end