怎么判断某个cell是否显示在屏幕上

1、首先，在成为某个视图的子视图时，先移除之前的kVO，然后对视图层级中所有class为UIScrollView的contentSize添加KVO。

2、然后，输入程序- (void)didMoveToSuperview { [self unKVO]; UI蕺清寤凯View *aView = self.superview; while (aView) { if ([aView isKindOfClass:[UIScrollView class]]) { [self observer:aView forKeyPath:@"contentSize" options:NSKeyValueObservingOptionNew context:(void *)__LINE__]; } aView = aView.superview; } }

3、然后，需要设置TableViewseparatorStyle属性UITableViewCellSeparatorStyleNone即除划。代码：tableView.separatorStyle = UITableViewCellSeparatorStyleNone;

4、当然，如果记录KVO了哪些视图的，方便及时移除：- (BOOL)isDisplayedInScreen{ if (self == nil) { return FALSE; }CGRect screenRect = [UIScreen mainScreen].bounds;

5、然后，打印监测到的值变化：static NSMutableArray *receiverArr; stat足毂忍珩ic SunTableViewCell *cell; - (void)observer:(NSObject *)receiver forKeyPath:(NSString *)keyPath options:(NSKeyValueObservingOptions)options context:(void *)context { if (cell && cell != self) { return; } cell = self; [receiver addObserver:self forKeyPath:keyPath options:options context:context]; if (!receiverArr) { receiverArr = [NSMutableArray array]; } [receiverArr addObject:receiver]; } - (void)dealloc { [self unKVO];

6、最后，获取 该view与window 交叉的 Rect CGRect intersectionRect = CGRectIntersection(rect, screenRect); if (CGRectIsEmpty(intersectionRect) || CGRectIsNull(intersectionRect)) {return FALSE; } return TRUE;}