IOS实现自定义透明背景的tabbar

```
//  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;
}


```