鍵值觀察者模式KVO--為UIImageView新增KVO
阿新 • • 發佈:2019-02-07
UIImagVIew * coverImage = nil;
/*........
........相關程式碼.......
........
*/
//為coverImage的image屬性新增KVO,新增自己為屬性變化的觀察者
[coverImage addObserver:self forKeyPath:@"image" options:0 context:nil];
//KVO的回撥函式,當keyPath發生變化時呼叫
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
if ([keyPath isEqualToString:@"image"]) {
//如果發生變化,進行相關處理
..........
}
}
- (void)dealloc { //移除觀察者 [coverImage removeObserver:self forKeyPath:@"image"]; }