UIView *bgView = [[UIView alloc]initWithFrame:CGRectMake(0, 304, SCREEN_WIDTH, SCREEN_HEIGHT)];
    bgView.backgroundColor = COLOR_A(0, 0, 1, 0.5);
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(hiddenBgView:)];
    tap.delegate = self;
    [bgView addGestureRecognizer:tap];

本類繼承 UIGestureRecognizerDelegate
重寫UIGestureRecognizerDelegate代理方法

#pragma mark 手勢代理
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch
{//_tab1,_tab2,_tab3 不需要響應的子view
    if ([touch.view isDescendantOfView:_tab1] ||[touch.view isDescendantOfView:_tab2]||[touch.view isDescendantOfView:_tab3]) {
        return NO;
    }
    return YES;
}