关于UITabBar各部分自定义的代码片段

一、自定义TabBar选项卡背景
默认UITabBarController的TabBar背景是黑色的，如何自定义成背景图片呢？

UITabBarController *tabBarController = [[UITabBarController alloc] init];
// 获取选项卡控制器视图的所有子视图，保存到一数组中
NSArray *array = [tabBarController.view subviews];
// 索引值为1的应该就是TabBar
UITabBar  *tabBar = [array objectAtIndex:1];

// UIImage *image = [UIImage imageNamed:@"tabbarbg.png"];
UIImage *image = [UIImage imageWithContentsOfFile:sourcePath];
tabBar.layer.contents = (id)image.CGImage;

或者：

tabBarController = [[UITabBarController alloc] init];
[tabBarController setViewControllers: view_manager];

UIImageView *tab_imgv = [UIImageView alloc] initWithImage:[UIImage imageNamed:@"tabbar_bg.png"]];
tab_imgv.frame = CGRectMake(0,0,320,49);
tab_imgv.contentMode = UIViewContentModeScaleToFill;
// 为什么atIndex是1，看SDK
[[tabBarController tabBar] insertSubview:tab_imgv atIndex:1];
[tab_imgv release];
[view_manager release];

或者： 

UITabBarController *tabBarController = [[UITabBarController alloc] init];
// 初始化一矩形视图框架
CGRect frame = CGRectMake(0,0,320,49);
UIView *v = [[UIView alloc] initWithFrame:frame];
// 以图片为平铺的颜色模板，初始化颜色
UIImage *img = [UIImage imageNamed:@"tabbarbg.png"];
UIColor *color = [[UIColor alloc] initWithPatternImage:img];
// 设置视图背景色
v.backgroundColor = color;
// 将视图插入到选项卡栏底层
[tabBarController.tabBar insertSubview:v atIndex:0];

tabBarController.tabBar.opaque = YES;
[color release];
[v release];

或者：在UITabBarController子类中重写init方法来初始化

- (id)init {
   if(self=[super init]){
       //方法一
     UIImageView *imgv = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"tabbarbg.png"]];
      imgv.frame = CGRectMake(0,0,self.tabBar.frame.size.width,self.tabBar.frame.size.height);
      imgv.contentMode = UIViewContentModeScaleToFill;
      // imgv.frame = CGRectOffset(imgv.frame,0,1);
      [[self tabBar] insertSubview:imgv atIndex:0];
      [imgv release];

      // 方法二
     CGRect frame = CGRectMake(0,0,self.view.bounds.size.width,49);
      UIView *view = [[UIView alloc] initWithFrame:frame];
      UIImage *tabImage = [UIImage imageNamed:@"tabbg.png"];
      UIColor *color = [[UIColor alloc] initWithPatternImage:tabImage];
      [view setBackgroundColor:color];
      [color release];
      [[self tabBar] insertSubview:view atIndex:0];
      [view release];
   }
}

当然在iOS5开始就最方便了，在iOS5中提供了一个API来设置UITabBar的背景图片，以及表示选中的图片。

UIImage *tabBackground = [[UIImage imageNamed:@"tab_bg.png"] resizableImageWithCapInsets:UIEdgeInsetsMake(0, 0, 0, 0)];
[[UITabBar appearance] setBackgroundImage:tabBackground];
[[UITabBar appearance] setSelectionIndicatorImage:[UIImage imageNamed:@"tab_select_indicator.png"]];

二、隐藏TabBar

• 隐藏系统TabBar，但仍占位置。
  

  - (void)hideExsitingTabBar {
      for(UIView *view in self.view.subviews)
      {
           if([view isKindOfClass:[UITabBar  class]])
           {
                view.hidden = YES;
                break;
            }
       }
  }

• 彻底隐藏TabBar：如从一个有TabBar控制器的视图转入另外一新视图，且没有上一视图的TabBar。
  

  nextViewController.hidesBottomBarWhenPushed = YES;
  [self.navigationController pushViewController:nextViewController animated:NO];