将视图显示在最前方
[self.view addSubview:view]; [self.view bringSubviewToFront:view];
下拉取消回弹效果
- (void)scrollViewDidScroll:(UIScrollView *)scrollView{
//限制下拉没有回弹效果
if (scrollView.contentOffset.y <= 0){
CGPoint point = scrollView.contentOffset;
point.y = 0;
[scrollView setContentOffset:point];
}
}
检测某个API是否可用
1.使用respondsToSelector:方法检测是否有某个方法 respondsToSelector:@selector(method)
- 使用<objc/runtime.h>检测是否有某个属性 if (class_getProperty([ClassName class], “propertyName”)) { // it has that property! }