如何在故事板中的几个视图之间传递对象，iOS开发 [英] How to pass object between several views in storyboard, iOS Dev

问题描述

我搜索过这个，但答案太简单了，不能满足我：（

I have searched for this but the answer is too simple to satisfy me :(

我想传递一个 NSManagedObjectContext 从 TabBarController 几乎所有的视图控制器在我的应用程序。详细地说，我的故事板结构是这样：

I want to pass a NSManagedObjectContext from TabBarController to almost every view controllers in my app. In detail, my storyboard structure is kind of like this:

TabBarController >>>几个标签项视图（这很容易通过，只是传递一次在视图控制器）。但我有另一个关系： TabBarController （上面提到的）>>> NavigationController >>> TableViewControllerOne >>> TableViewControllerTwo ，

TabBarController >>> several tab items views ( this is easy to pass, just pass one time in according view controllers). But I have another relation: TabBarController(the one mentioned above) >>> NavigationController >>> TableViewControllerOne >>> TableViewControllerTwo,

现在是灾难，因为基本上我必须将 c> 到 TableViewControllerOne 和的 NSManagedObjectContext TableViewControllerTwo ....这可能涉及很多 prepareSegue：sender ，并且不容易管理。

now it's disaster. Because basically I have to transfer the NSManagedObjectContext instance from the NavigationController to TableViewControllerOne and to TableViewControllerTwo....that could involve a lot of prepareSegue:sender and it's not easy to manage.

所以我的问题是：在iOS开发中，有没有办法创建一个全局对象，我可以在我的整个应用程序轻松访问？从苹果的官方模板的主细节视图使用核心数据，它实例化 NSManagedObjectContext 在应用程序代理，传递给主视图控制器。如果我必须在几个视图传递后使用此对象怎么办？哇，这是很多代码要做。

So my question is: in iOS development, is there a way that I can create a "global" object that I can easily access in my entire app? From apple's official template for master-detail view using core data, it instantiates the NSManagedObjectContext in app delegate, passing it to master view controller. What if I have to use this object after several view pass? Wow, that's a lot of code to do.

希望我明白了，有人可以帮助:)
非常感谢。

Hope I made myself clear and someone could help :) Thanks a lot.

推荐答案

我个人喜欢使用 ModelController 类的单例对象，堆栈相关对象（上下文，模型和商店协调器）和帮助方法都在一个地方，我可以从任何地方访问我的视图控制器。像这样：

Personally I like to use a singleton object of a ModelController class where I can put Core Data stack-related objects (Context, Model and Store Coordinator) and helper methods all in one place, that I can then access from anywhere in my view controllers. Something like this:

@implementation ModelController

- (NSManagedObjectModel *)managedObjectModel
{
    // ...
    return _managedObjectModel;
}

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
    // ...
    return _persistentStoreCoordinator;
}

- (NSManagedObjectContext *)contextForCurrentThread
{
    NSManagedObjectContext *context = [[NSThread currentThread] threadDictionary][@"threadManagedObjectContext"];
    if (context == nil)
    {
        context = [[NSManagedObjectContext alloc] init];
        [context setPersistentStoreCoordinator:self.persistentStoreCoordinator];

        [[NSThread currentThread] threadDictionary][@"threadManagedObjectContext"] = context;
    }
    return context;
}

- (void)resetCoreDataStack
{
    [[[NSThread currentThread] threadDictionary] removeObjectForKey:@"threadManagedObjectContext"];
    self.persistentStoreCoordinator = nil;
    self.managedObjectModel = nil;
}

+ (ModelController *)sharedModelController
{        
    static ModelController *modelController;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        modelController = [[ModelController alloc] init];
    });
    return modelController;
}
@end

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