KVO - 观察自定义属性值

1 . 声明属性&注册监听

{ BOOL isOk; }

[self addObserver:self forKeyPath:@"isOk" options:0 context:nil];

2 .改变属性值

[self willChangeValueForKey:@"isOk"];

// 只有自己去定义时才需要如此设置

isOk = isOk?NO:YES;

[self didChangeValueForKey:@"isOk"];

3 . 监听值改变

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context {

if ([keyPath isEqualToString:@"isOk"]) {

NSLog(@"%d currentThread:%f",isOk,[NSThread currentThread]);

} else { // 一定要调用

[super observeValueForKeyPath:keyPath ofObject:object change:change context:context];

}

}