自定义的tabbar颜色怎么一半灰色一半黑色啊？？

：

(id)initWithNibName:(NSString )nibNameOrNil bundle:(NSBundle )nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {

  [self.tabBar setHidden:YES];//设置tabbar隐藏
   self.tabBar.opaque=YES;//设置不透明度

// [self.tabBar setBackgroundColor:[UIColor whiteColor]];//设置系统自带的背景颜色

  UITabBar *tabBarView=[[UITabBar alloc]initWithFrame:CGRectMake(0, 300, 320, 44)];

// [tabBarView setTintColor:[UIColor colorWithPatternImage:[UIImage imageNamed:@"aifang_79@2x.png"]]];

  [self.view addSubview:tabBarView];
  [tabBarView release];

}
return self;
}