将代码放到另一个线程中。

To fix this problem I changed the code to put it in another thread.

dispatch_queue_t mainQueue = dispatch_get_main_queue();
        dispatch_async(mainQueue, ^{

            NSFileManager *fileManager = [NSFileManager defaultManager];
            NSURL *localStore = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:dataFileName];
            NSURL *iCloud = [fileManager URLForUbiquityContainerIdentifier:nil];

            if (iCloud)
            {
                //NSLog(@"iCloud is working");

                NSURL *iCloudLogsPath = [NSURL fileURLWithPath:[[iCloud path] stringByAppendingPathComponent:iCloudLogsDirectoryName]];

                /*NSLog(@"iCloudEnabledAppID = %@",iCloudEnabledAppID);
                 NSLog(@"dataFileName = %@", dataFileName);
                 NSLog(@"iCloudDataDirectoryName = %@", iCloudDataDirectoryName);
                 NSLog(@"iCloudLogsDirectoryName = %@", iCloudLogsDirectoryName);
                 NSLog(@"iCloud = %@", iCloud);
                 NSLog(@"iCloudLogsPath = %@", iCloudLogsPath);*/

                if ([fileManager fileExistsAtPath:[[iCloud path] stringByAppendingPathComponent:iCloudDataDirectoryName]] == NO) {
                    NSError *fileSystemError;
                    [fileManager createDirectoryAtPath:[[iCloud path] stringByAppendingPathComponent:iCloudDataDirectoryName]
                           withIntermediateDirectories:YES
                                            attributes:nil
                                                 error:&fileSystemError];

                    if (fileSystemError != nil) {
                        NSLog(@"Error creating database directory %@", fileSystemError);
                    }
                }

                NSString *iCloudData = [[[iCloud path]
                                         stringByAppendingPathComponent:iCloudDataDirectoryName]
                                        stringByAppendingPathComponent:dataFileName];

                //NSLog(@"iCloudData = %@", iCloudData);

                NSMutableDictionary *options = [NSMutableDictionary dictionary];
                [options setObject:[NSNumber numberWithBool:YES] forKey:NSMigratePersistentStoresAutomaticallyOption];
                [options setObject:[NSNumber numberWithBool:YES] forKey:NSInferMappingModelAutomaticallyOption];
                [options setObject:iCloudEnabledAppID forKey:NSPersistentStoreUbiquitousContentNameKey];
                [options setObject:iCloudLogsPath forKey:NSPersistentStoreUbiquitousContentURLKey];

                [psc lock];

                [psc addPersistentStoreWithType:NSSQLiteStoreType
                                  configuration:nil
                                            URL:[NSURL fileURLWithPath:iCloudData]
                                        options:options
                                          error:nil];

                [psc unlock];

            } else {

                NSLog(@"iCloud is NOT working - using a local store");
                NSMutableDictionary *options = [NSMutableDictionary dictionary];
                [options setObject:[NSNumber numberWithBool:YES] forKey:NSMigratePersistentStoresAutomaticallyOption];
                [options setObject:[NSNumber numberWithBool:YES] forKey:NSInferMappingModelAutomaticallyOption];

                [psc lock];

                [psc addPersistentStoreWithType:NSSQLiteStoreType
                                  configuration:nil
                                            URL:localStore
                                        options:options
                                          error:nil];

                [psc unlock];
            }
        });