iOS UITabBar底部中间突出圆角

- (void)createTabBarBGLayer
{
    _tabBarGBLayer = [CAShapeLayer layer];

    UIBezierPath *bezierPath = [UIBezierPath bezierPath];
    [bezierPath moveToPoint:CGPointMake(-1, 0)];
    [bezierPath addLineToPoint:CGPointMake(windWidth / 2 - 25, 0)];
    [bezierPath addQuadCurveToPoint:CGPointMake(windWidth / 2 + 25, 0) controlPoint:CGPointMake(windWidth / 2, -30)];
    [bezierPath addLineToPoint:CGPointMake(windWidth + 1, 0)];
    [bezierPath addLineToPoint:CGPointMake(windWidth + 1, 100)];
    [bezierPath addLineToPoint:CGPointMake(-1, 120)];
    [bezierPath closePath];

    _tabBarGBLayer.path = bezierPath.CGPath;
    _tabBarGBLayer.lineWidth = 0.5;
    _tabBarGBLayer.fillColor = [UIColor redColor].CGColor;
    _tabBarGBLayer.strokeColor = [UIColor redColor].CGColor;
    [self.tabBar.layer insertSublayer:_tabBarGBLayer atIndex:0];
}