ios tabbar添加阴影

- (void)awakeFromNib {
    [super awakeFromNib];
    [self setTarBarStyle];
    [self.tabBarController.tabBar setBackgroundImage:[UIImage new]];
    [self.tabBarController.tabBar setShadowImage:[UIImage new]];
    
    [self dropShadowWithOffset:CGSizeMake(0, -2)
                        radius:2
                         color:[UIColor blackColor]
                       opacity:0.1];
}

- (void)dropShadowWithOffset:(CGSize)offset
                      radius:(CGFloat)radius
                       color:(UIColor *)color
                     opacity:(CGFloat)opacity {
    CGMutablePathRef path = CGPathCreateMutable();
    CGPathAddRect(path, NULL, self.tabBarController.tabBar.bounds);
    self.tabBarController.tabBar.layer.shadowPath = path;
    CGPathCloseSubpath(path);
    CGPathRelease(path);
    
    self.tabBarController.tabBar.layer.shadowColor = color.CGColor;
    self.tabBarController.tabBar.layer.shadowOffset = offset;
    self.tabBarController.tabBar.layer.shadowRadius = radius;
    self.tabBarController.tabBar.layer.shadowOpacity = opacity;
    
    self.tabBarController.tabBar.clipsToBounds = NO;
}