问题：
用Interface Builder为UITabBarController 设置selected image，运行起来后提示：Could not load the "(null)" image referenced from a nib in the bundle with identifier
修改方法：
获取制定的tabbar实例，用代码修改
<pre><code>
-
(BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
//storyboard每次都创建个新的实例对象，因此需要呈现它 否则不显示
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"main" bundle:[NSBundle mainBundle]];
UITabBarController * tabBarController = [storyboard instantiateViewControllerWithIdentifier:@"TabBarController"];
self.window.rootViewController = tabBarController;NSArray *imageArray = @[@"ic_tabbar_home",@"ic_tabbar_oversea_red",@"ic_tabbar_faxian_red", @"ic_tabbar_shopping_cart", @"ic_tabbar_my"];
int i = 0;
NSArray *itemArray = tabBarController.tabBar.items;
for (UITabBarItem *item in itemArray) {
UIImage *image = [UIImage imageNamed:imageArray[i++]];
item.selectedImage = image;
}
tabBarController.tabBar.tintColor = [UIColor redColor];return YES;
}
</code></pre>
参考：How to set selected images for UITabBarItem in UITabBarController
