iOS 把tabbar背景设置为透明

//    UIImageView *imageView = [[UIImageView alloc]initWithFrame:CGRectMake(0, 0, kScreenW, tabBarHeight + 5)];
//    [imageView setImage:[self createImageWithColor:[UIColor clearColor]]];
//    [imageView setContentMode:UIViewContentModeScaleToFill];
//    [self.tabBar insertSubview:imageView atIndex:0];

//覆盖原生Tabbar的上横线
//    [[UITabBar appearance] setShadowImage:[self createImageWithColor:[UIColor clearColor]]];
//背景图片为透明色
//    [[UITabBar appearance] setBackgroundImage:[self createImageWithColor:[UIColor clearColor]]];
self.tabBar.backgroundColor = [UIColor clearColor];
//设置为半透明
self.tabBarController.tabBar.translucent = YES;

-(UIImage*) createImageWithColor:(UIColor*) color
{
CGRect rect=CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [color CGColor]);
CGContextFillRect(context, rect);
UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return theImage;
}