设置UITabBarController的背景颜色

 if (IOS7) {
        self.tabBarController.tabBar.barTintColor = kTAB_BAR_GB_COLOR;
    }else{
        self.tabBarController.tabBar.tintColor = kTAB_BAR_GB_COLOR;
        [[UITabBar appearance] setBackgroundImage:[ZQUtiles imageWithColor:kTAB_BAR_GB_COLOR size:CGSizeMake(29, 1)]];//设置背景，修改颜色是没有用的

        [[UITabBar appearance] setSelectionIndicatorImage:[ZQUtiles imageWithColor:kTAB_BAR_GB_COLOR size:CGSizeMake(29, 1)]];

        [[UITabBar appearance] setShadowImage:[ZQUtiles imageWithColor:kDEFAULT_BG_COLOR size:CGSizeMake(29, 1)]];//隐藏那条黑线

        [[UITabBarItem appearance] setTitlePositionAdjustment:UIOffsetMake(0, -2)];
    }