在iOS8系统下，UITabbar上的item自定义背景色和图片问题

解决方法：

//选择的图片

UITabBar *tabBar = self.tabBar;

UITabBarItem *tabBarItem1 = [tabBar.items objectAtIndex:0];

UITabBarItem *tabBarItem2 = [tabBar.items objectAtIndex:1];

UITabBarItem *tabBarItem3 = [tabBar.items objectAtIndex:2];

tabBarItem1.title = @"title1";

tabBarItem2.title = @"title2";

UIImage* selectedImage = [UIImage imageNamed:@"xxxx.png"];

UIImage* unselectedImage = [UIImage imageBunded:unselImgName];

//声明这张图片用原图(别渲染)

selectedImage = [selectedImage imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];

unselectedImage = [unselectedImage imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];

[tabBarItem1 setFinishedSelectedImage:selectedImage withFinishedUnselectedImage:unselectedImage ];

[tabBarItem2 setFinishedSelectedImageselectedImage withFinishedUnselectedImage:unselectedImage];