［已解决］swift设置Tab的背景色

        //6. create tabs
        let viewConversation    = ConversationViewController()
        let viewContact         = ContactViewController()
        let viewFile            = FileViewController()
        let viewFavorite        = FavoriteViewController()
        let viewMy              = MyViewController()

        let nvcConversation = UINavigationController(rootViewController: viewConversation)
        nvcConversation.tabBarItem = UITabBarItem(title: mainTabs[0], image: UIImage(named:"tab_conversation"), tag:0)
        nvcConversation.tabBarItem.selectedImage = UIImage(named: "tab_conversation_selected")
        //nvcConversation.tabBarItem.badgeValue = "3"

        let nvcContact = UINavigationController(rootViewController: viewContact)
        nvcContact.tabBarItem = UITabBarItem(title: mainTabs[1], image: UIImage(named:"tab_contact"), tag:1)
        nvcContact.tabBarItem.selectedImage = UIImage(named: "tab_contact_selected")

        let nvcFile = UINavigationController(rootViewController: viewFile)
        nvcFile.tabBarItem = UITabBarItem(title: mainTabs[2], image: UIImage(named:"tab_file"), tag:2)
        nvcFile.tabBarItem.selectedImage = UIImage(named: "tab_file_selected")

        let nvcFavorite = UINavigationController(rootViewController: viewFavorite)
        nvcFavorite.tabBarItem = UITabBarItem(title: mainTabs[3], image: UIImage(named:"tab_favorite"), tag:3)
        nvcFavorite.tabBarItem.selectedImage = UIImage(named: "tab_favorite_selected")

        let nvcMy = UINavigationController(rootViewController: viewMy)
        nvcMy.tabBarItem = UITabBarItem(title: mainTabs[4], image: UIImage(named:"tab_my"), tag:4)
        nvcMy.tabBarItem.selectedImage = UIImage(named: "tab_my_selected")

        self.viewControllers = [nvcConversation, nvcContact, nvcFile, nvcFavorite, nvcMy]

        //set bar item font
        let barItemFont = FontMainTab
        for nvcController in self.viewControllers!{
            nvcController.tabBarItem.setTitleTextAttributes([NSFontAttributeName: barItemFont], forState: UIControlState.Normal)
        }

［解决过程］

1.搜：

参考：

swift – IOS 8 Tab Bar Item Background Colour – Stack Overflow

tabview – Changing Tab Bar Color (Swift) – Stack Overflow

ios – Set background color of active tab bar item in Swift – Stack Overflow

Background color on Tab Bar question.：swift

试了试：

        UITabBar.appearance().tintColor = UIColor.purpleColor()

 效果：

不是所要的。

       UITabBar.appearance().tintColor = UIColor.purpleColor()
        UITabBar.appearance().barTintColor = UIColor.yellowColor()

 效果：

达到所需要的效果了。

再去调节：

let ColorMainTabBackground:UIColor = UIColor(hexString: "#f6f6f6")!

        //UITabBar.appearance().tintColor = UIColor.purpleColor()
        UITabBar.appearance().barTintColor = ColorMainTabBackground

最终的效果：

官网的解释是：

 

［总结］

想要设置tab的背景色，实际上是：

设置UITabBar的背景色，对应设置代码为：

UITabBar.appearance().barTintColor = UIColor.yellowColor()

即可。