MagicalRecord完成塊在導入時保存所有內容

Question

當有人登錄我的應用程序時，會創建一個帶有JSON響應的調用，然後使用此數據將其導入到使用MagicalRecord的Core Data中。 所有導入完成後，調用一個名爲success的塊，讓我的LoginViewController知道一切正常，並停止UIActivityIndicatorView，這樣就可以創建一個segue。

它指向一個新的ViewController，它有一個UITableView來顯示剛導入的數據。

我的問題是，這個成功塊被稱爲之前 MagicalRecord完成與節省。因此，UITableView尚未收到要顯示的訂單對象。

這是我實現saveWithBlockAndWait塊是如下：

[MagicalRecord saveWithBlockAndWait:^(NSManagedObjectContext *localContext) { 

    NSDictionary *users = [responseObject valueForKeyPath:@"responses.user"]; 
    [User importFromObject:users inContext:localContext]; 

    NSArray *orders = [responseObject valueForKeyPath:@"responses.orders"]; 
    [Order importFromArray:orders inContext:localContext];  

    NSLog(@"SAVING DONE"); 
}]; 

在我OrdersViewController（女巫是ViewController中有許多人也賽格瑞）是另一個NSLog，並且它是這裏的問題可能是。

Xcode的輸出顯示SAVING DONE已被調用，但在我的AFNetworking調用之後。這意味着所有的數據都不會保存，並且不準備顯示 - 即使是saveWithBlockAndWait。此外，輸出顯示有0行。

該應用程序在我的第二次啓動時完美運行。它僅在第一次登錄我有這個問題

2015-05-04 19:16:31.617 xxxxx[35555:5569667] +[NSManagedObjectContext(MagicalRecord) MR_contextWithStoreCoordinator:](0xff4a04) -> Created Context UNNAMED 
2015-05-04 19:16:31.618 xxxxx[35555:5569667] +[NSManagedObjectContext(MagicalRecord) MR_setRootSavingContext:](0xff4a04) Set Root Saving Context: <NSManagedObjectContext: 0x7aecdf10> 
2015-05-04 19:16:31.618 xxxxx[35555:5569667] +[NSManagedObjectContext(MagicalRecord) MR_newMainQueueContext](0xff4a04) Created Main Queue Context: <NSManagedObjectContext: 0x7aff4280> 
2015-05-04 19:16:31.618 xxxxx[35555:5569667] +[NSManagedObjectContext(MagicalRecord) MR_setDefaultContext:](0xff4a04) Set Default Context: <NSManagedObjectContext: 0x7aff4280> 
2015-05-04 19:16:46.104 xxxxx[35555:5569667] POST 'secret' 
2015-05-04 19:16:47.237 xxxxx[35555:5569667] 200 'secret' [1.1324 s] 
2015-05-04 19:16:47.258 xxxxx[35555:5569667] POST 'secret' 
2015-05-04 19:16:47.880 xxxxx[35555:5569667] 200 'secret' [0.6215 s] 
2015-05-04 19:16:47.901 xxxxx[35555:5569667] SAVING DONE 
2015-05-04 19:16:47.902 xxxxx[35555:5569667] -[NSManagedObjectContext(MagicalSaves) MR_saveWithOptions:completion:](0x7ae251e0) → Saving <NSManagedObjectContext (0x7ae251e0): *** UNNAMED ***> on *** MAIN THREAD *** 
2015-05-04 19:16:47.903 xxxxx[35555:5569667] -[NSManagedObjectContext(MagicalSaves) MR_saveWithOptions:completion:](0x7ae251e0) → Save Parents? 1 
2015-05-04 19:16:47.903 xxxxx[35555:5569667] -[NSManagedObjectContext(MagicalSaves) MR_saveWithOptions:completion:](0x7ae251e0) → Save Synchronously? 1 
2015-05-04 19:16:47.903 xxxxx[35555:5569667] -[NSManagedObjectContext(MagicalRecord) MR_contextWillSave:](0x7ae251e0) Context UNNAMED is about to save. Obtaining permanent IDs for new 2 inserted objects 
2015-05-04 19:16:47.906 xxxxx[35555:5569667] -[NSManagedObjectContext(MagicalSaves) MR_saveWithOptions:completion:](0x7aecdf10) → Saving <NSManagedObjectContext (0x7aecdf10): *** BACKGROUND SAVING (ROOT) ***> on *** MAIN THREAD *** 
2015-05-04 19:16:47.906 xxxxx[35555:5569667] -[NSManagedObjectContext(MagicalSaves) MR_saveWithOptions:completion:](0x7aecdf10) → Save Parents? 1 
2015-05-04 19:16:47.906 xxxxx[35555:5569667] -[NSManagedObjectContext(MagicalSaves) MR_saveWithOptions:completion:](0x7aecdf10) → Save Synchronously? 1 
2015-05-04 19:16:47.907 xxxxx[35555:5569667] -[NSManagedObjectContext(MagicalRecord) MR_contextWillSave:](0x7aecdf10) Context BACKGROUND SAVING (ROOT) is about to save. Obtaining permanent IDs for new 2 inserted objects 
2015-05-04 19:16:47.909 xxxxx[35555:5569667] __70-[NSManagedObjectContext(MagicalSaves) MR_saveWithOptions:completion:]_block_invoke21(0x7aecdf10) → Finished saving: <NSManagedObjectContext (0x7aecdf10): *** BACKGROUND SAVING (ROOT) ***> on *** MAIN THREAD *** 
2015-05-04 19:16:47.909 xxxxx[35555:5569667] All data has been setup sucessfully 
2015-05-04 19:16:47.909 xxxxx[35555:5569667] Perform Segue To LoginSucessSegue from LoginViewController 
2015-05-04 19:16:47.945 xxxxx[35555:5570918] -[NSManagedObjectContext(MagicalSaves) MR_saveWithOptions:completion:](0x7ae19130) → Saving <NSManagedObjectContext (0x7ae19130): *** UNNAMED ***> on *** BACKGROUND THREAD *** 
2015-05-04 19:16:47.952 xxxxx[35555:5569667] Number of rows: 0 
2015-05-04 19:16:47.957 xxxxx[35555:5570918] -[NSManagedObjectContext(MagicalSaves) MR_saveWithOptions:completion:](0x7ae19130) → Save Parents? 1 
2015-05-04 19:16:47.957 xxxxx[35555:5570918] -[NSManagedObjectContext(MagicalSaves) MR_saveWithOptions:completion:](0x7ae19130) → Save Synchronously? 0 
2015-05-04 19:16:47.958 xxxxx[35555:5570918] -[NSManagedObjectContext(MagicalRecord) MR_contextWillSave:](0x7ae19130) Context UNNAMED is about to save. Obtaining permanent IDs for new 4 inserted objects 
2015-05-04 19:16:47.962 xxxxx[35555:5570918] -[NSManagedObjectContext(MagicalSaves) MR_saveWithOptions:completion:](0x7aecdf10) → Saving <NSManagedObjectContext (0x7aecdf10): *** BACKGROUND SAVING (ROOT) ***> on *** BACKGROUND THREAD *** 
2015-05-04 19:16:47.963 xxxxx[35555:5570918] -[NSManagedObjectContext(MagicalSaves) MR_saveWithOptions:completion:](0x7aecdf10) → Save Parents? 1 
2015-05-04 19:16:48.023 xxxxx[35555:5570918] -[NSManagedObjectContext(MagicalSaves) MR_saveWithOptions:completion:](0x7aecdf10) → Save Synchronously? 0 
2015-05-04 19:16:48.024 xxxxx[35555:5570924] -[NSManagedObjectContext(MagicalRecord) MR_contextWillSave:](0x7aecdf10) Context BACKGROUND SAVING (ROOT) is about to save. Obtaining permanent IDs for new 4 inserted objects 
2015-05-04 19:16:48.026 xxxxx[35555:5570924] __70-[NSManagedObjectContext(MagicalSaves) MR_saveWithOptions:completion:]_block_invoke21(0x7aecdf10) → Finished saving: <NSManagedObjectContext (0x7aecdf10): *** BACKGROUND SAVING (ROOT) ***> on *** BACKGROUND THREAD *** 

是對saveWithBlockAndWait得到執行錯誤的，因爲它不是爲我工作？關於如何解決這個問題的建議或解決方案將非常棒。

Answer 1

您的日誌似乎正確。首先它運行你的塊，然後將所有內容保存到數據庫，然後當前線程繼續執行。

您使用同步方法。同步方法阻塞當前線程直到它們完成執行。如果您想更新界面，您必須在saveWithBlockAndWait之後執行此操作，或使用提供完成處理程序的「save」方法的異步版本。

[MagicalRecord saveWithBlockAndWait:^(NSManagedObjectContext *localContext) { 

    NSDictionary *users = [responseObject valueForKeyPath:@"responses.user"]; 
    [User importFromObject:users inContext:localContext]; 

    NSArray *orders = [responseObject valueForKeyPath:@"responses.orders"]; 
    [Order importFromArray:orders inContext:localContext]; 
}]; 

NSLog(@"Saving done."); 

通常，最好使用異步方法來避免阻塞主線程。

[MagicalRecord saveWithBlock:^(NSManagedObjectContext *localContext) { 


    // create or update CoreData models 


} completion:^(BOOL contextDidSave, NSError *error) { 
    if(error) { 
     NSLog(@"Failed to save data"); 
     return; 
    } 

    NSLog(@"Saving done."); 

    [self.activityIndicator stopAnimating]; 
}];