扩大Button的响应区域

- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent*)event
{
    CGRect bounds = self.bounds;
    //若原热区小于44x44，则放大热区，否则保持原大小不变
CGFloat widthDelta = MAX(44.0 - bounds.size.width, 0);
CGFloat heightDelta = MAX(44.0 - bounds.size.height, 0);
bounds = CGRectInset(bounds, -0.5 * widthDelta, -0.5 * heightDelta);
return CGRectContainsPoint(bounds, point);
}