應用程序在不同的線程

Question

保存時，我有這將創建一個單獨的線程的方法崩潰：

// Create thread 
dispatch_queue_t uniqueQueue = dispatch_queue_create("Unique Email Queue", NULL); 

// Run block on another thread called downloadQueue 
dispatch_async(uniqueQueue, ^{ 

    // Save to core data for redundancy 
     User *coreDataUser = [NSEntityDescription insertNewObjectForEntityForName:@"User" inManagedObjectContext:self.managedObjectContext]; 

     coreDataUser.username = [emailStr lowercaseString]; 
     coreDataUser.email = emailStr; 
     coreDataUser.name = nameStr; 

     NSError *error; 

     if (![self.managedObjectContext save:&error]) 
     { 
      NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]); 
     }    
    } 

的應用總是崩潰在這條線：

User *coreDataUser = [NSEntityDescription insertNewObjectForEntityForName:@"User" inManagedObjectContext:self.managedObjectContext]; 

我使用本教程作爲參考：http://www.codigator.com/tutorials/ios-core-data-tutorial-with-example/

我錯過了什麼？

Answer 1

記住 - CoraData不是線程安全的!!!!!

如果你想爲你的managedObjectContext分開線程，你必須在這個線程上創建一個線程。要調用正確的上下文，您必須使用performBlock塊來運行它。你的情況：

[self.managedObjectContext performBlock:^{ 
     User *coreDataUser = [NSEntityDescription insertNewObjectForEntityForName:@"User" inManagedObjectContext:self.managedObjectContext]; 

     coreDataUser.username = [emailStr lowercaseString]; 
     coreDataUser.email = emailStr; 
     coreDataUser.name = nameStr; 

     NSError *error; 

     if (![self.managedObjectContext save:&error]) 
     { 
      NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]); 
     } 
}]; 

但要記住，如果你在mainThread創設情境，你的塊也mainThread執行。

Answer 2

NSManagedObjectContext不是線程安全的，請嘗試在異步塊的一側創建新的moc。 嘗試：「找不到這個型號命名爲‘用戶’實體」

// Create thread 
dispatch_queue_t uniqueQueue = dispatch_queue_create("Unique Email Queue", NULL); 

// Run block on another thread called downloadQueue 
dispatch_async(uniqueQueue, ^{ 

    // Save to core data for redundancy 
     NSManagedObjectContext *context = [[NSManagedObjectContext alloc] init]; 
    [context setPersistentStoreCoordinator:persistentStoreCoordinator]; 

     User *coreDataUser = [NSEntityDescription insertNewObjectForEntityForName:@"User" inManagedObjectContext:context]; 

     coreDataUser.username = [emailStr lowercaseString]; 
     coreDataUser.email = emailStr; 
     coreDataUser.name = nameStr; 

     NSError *error; 

     if (![context save:&error]) 
     { 
      NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]); 
     }    
    } 

持久性存儲在你的AppDelegate