無法從現有核心數據數據庫中讀回

任何人都可以在這裏幫助我。我很困難。無法從現有核心數據數據庫中讀回

在我的代碼中，如果Documents位置中不存在文件;我創建商店，將數據放入其中並從中讀回。這工作正常。但是，如果文件已經存在於該位置，我無法從它讀回。我嘗試了很多，但我真的不確定它爲什麼不起作用。有些時候（實際上很少），非常相同的代碼將工作，但其他時間不會。

這是代碼。當它不起作用時，useDocument方法中的調試消息「End of useDocument」從不記錄。這是在UIManagedDocument上調用openWithCompletionHandler的方法。代碼進入方法，但從來沒有達到該方法的末尾！

- (void)setupFetchedResultsController 
{ NSLog(@"In setupFetchedResultsController"); 

NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"WorkOutTypes"]; 
request.sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"workoutName" ascending:YES]]; 


self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request 
                    managedObjectContext:self.workoutDatabase.managedObjectContext 
                     sectionNameKeyPath:nil 
                       cacheName:nil]; 

NSLog(@"End of setupFetchedResultsController"); 
} 

- (void)pushWorkoutDataIntoDocument:(UIManagedDocument *)document 
{ NSLog(@"In pushWorkoutDataIntoDocument"); 
dispatch_queue_t pushQ = dispatch_queue_create("Push data", NULL); 
dispatch_async(pushQ, ^{ 
    NSArray *workOuts = [NSArray arrayWithObjects:@"Squats", @"Bench Press", @"Overhead Press", @"Bent Over Rows", nil]; 
    [document.managedObjectContext performBlock:^{ 
     for (NSString *workout in workOuts) { 
      [WorkOutTypes workoutName:workout inManagedObjectContext:document.managedObjectContext]; 
     } 
    }];   
}); 
dispatch_release(pushQ); 
} 

- (void)useDocument 
{ NSLog(@"In useDocument"); 
NSLog(@"File path - %@", [self.workoutDatabase.fileURL path]); 
if (![[NSFileManager defaultManager] fileExistsAtPath:[self.workoutDatabase.fileURL path]]) { 
    NSLog(@"1"); 
    [self.workoutDatabase saveToURL:self.workoutDatabase.fileURL 
       forSaveOperation:UIDocumentSaveForCreating 
       completionHandler:^(BOOL success){ 
        [self setupFetchedResultsController]; 
        [self pushWorkoutDataIntoDocument:self.workoutDatabase]; 
       }]; 
} 
else 
    if (self.workoutDatabase.documentState == UIDocumentStateClosed) { 
     NSLog(@"2"); 
     [self.workoutDatabase openWithCompletionHandler:^(BOOL success){ 
      NSLog(@"handler called");[self setupFetchedResultsController];}]; 
    } 
    else 
     if (self.workoutDatabase.documentState == UIDocumentStateNormal) { 
      NSLog(@"3"); 
      [self setupFetchedResultsController]; 
     } 
NSLog(@"End of useDocument"); 

} 

- (void)setWorkoutDatabase:(UIManagedDocument *)workoutDatabase 
{ NSLog(@"In setWorkoutDatabase"); 
if (_workoutDatabase != workoutDatabase) { 
    _workoutDatabase = workoutDatabase; 
    [self useDocument]; 
} 
} 

- (void)viewWillAppear:(BOOL)animated 
{ 
[super viewWillAppear:animated]; 
// self.navigationItem.rightBarButtonItem = self.editButtonItem; 

if (!self.workoutDatabase) { 
    NSLog(@"Came in"); 
    NSURL *url = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject]; 
    url = [url URLByAppendingPathComponent:@"Default Workouts Database"]; 
    self.workoutDatabase = [[UIManagedDocument alloc] initWithFileURL:url]; 
    NSLog(@"URL - %@", [url path]); 
} 
if (self.workoutDatabase) { 
    NSLog(@"workoutDatabase created"); 
} 
else 
    NSLog(@"workoutDatabase not created"); 
}

來源

2012-04-19 OutOnAWeekend

現在就結束這個問題。我恢復爲使用傳統的核心數據堆棧而不是UIManagedDocument。這是相當不可靠的。

來源

2012-05-25 22:29:49 OutOnAWeekend

無法從現有核心數據數據庫中讀回

回答

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