在滑动的时候可能会出现 CGRectGetHeight(self.pendingAttributes.targetBounds) == CGRectGetHeight(self.pendingAttributes.sourceBounds)

[MrLiuYS]

CGFloat maxTranslation = CGRectGetHeight(self.pendingAttributes.targetBounds) - CGRectGetHeight(self.pendingAttributes.sourceBounds);
translation = MAX(0, translation);
translation = MIN(maxTranslation, translation);
progress = translation/maxTranslation;
因为 maxTranslation = 0 . 直接引起崩溃.

libc++abi.dylib: terminate_handler unexpectedly threw an exception