1，判断SuperView
1 - (void)willMoveToSuperview:(UIView *)newSuperview
2 {
3 [super willMoveToSuperview:newSuperview];
4
5 if (!newSuperview)
6 [self removeObservers];
7 else
8 [self addObservers];
9 }
2，判断Slider值改变之后在执行Event
_slider.continuous = NO;
原文：http://www.cnblogs.com/conan0919/p/5009514.html