如何在TabBased应用程序中将NSManagedObjectContext从AppDelegate分配给ViewController？ [英] How to assign NSManagedObjectContext from AppDelegate to ViewControllers in TabBased application?

问题描述

新手的问题在这里。

因为XCode不提供项目模板的TabBased应用程序与Core Data，所以我必须去切割和粘贴Core Data堆栈从其他模板到我的TabBased应用程序。

Since XCode doesn't provide project template for TabBased application with Core Data, so I have to go cutting and pasting Core Data stack from other templates to my TabBased application.

这是如何分配 NSManagedObjectContext 应用程序模板中的到到MasterViewController ：

This is how to assign NSManagedObjectContext object from AppDelegate to MasterViewController in Master-Detail application template:

// AppDelegate.m (Master-Detail template)

- (BOOL)application:(UIApplication *)application 
    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // Override point for customization after application launch.
    UINavigationController *navigationController = 
            (UINavigationController *)self.window.rootViewController;
    MasterViewController *controller = 
            (MasterViewController *)navigationController.topViewController;
    controller.managedObjectContext = self.managedObjectContext;
    return YES;
}

如何分配 NSManagedObjectContext

推荐答案

如果标签页bar控制器是根视图控制器，
主视图控制器在第一个选项卡上：

If the tab bar controller is the root view controller and the "master view controller" is on the first tab:

UITabBarController *tbc = (UITabBarController *)self.window.rootViewController;
MasterViewController *controller = (MasterViewController *)tbc.viewControllers[0];
controller.managedObjectContext = self.managedObjectContext;

更新：如果第一个标签使用导航控制器，插入一个步骤：

Update: If the first tab uses a navigation controller, you just have to insert one step:

UITabBarController *tbc = (UITabBarController *)self.window.rootViewController;
UINavigationController *nc = tbc.viewControllers[0];
YourViewController controller = (YourViewController *)nc.topViewController;
controller.managedObjectContext = self.managedObjectContext;

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