CoreData迁移问题

Question

我目前正在编写应用程序的下一个版本.

在旧版本中,没有CoreData sqlite

在新版本中,我们有一个本地CoreData sqlite数据库.

当我从头开始安装新版本的应用程序时,没有问题,商店就在那里,我可以查询.

但是,当我在具有上一版本的手机上安装应用程序时,我的查询会返回,但没有结果.

当我查看日志时,控制台中没有任何内容,并且不会返回任何错误.

   #import "CoreDataHelper.h"

@implementation CoreDataHelper
@synthesize store = _store;
@synthesize coordinator = _coordinator;


#pragma mark - 
#pragma mark - FILES
NSString *storeFileName = @"Reporting.sqlite";

#pragma mark - 
#pragma mark - PATHS
- (NSString *)applicationDocumentsDirectory {

    return [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];

}

- (NSURL *)applicationStoresDirectory {

    NSURL *storesDirectory = [[NSURL fileURLWithPath:[self applicationDocumentsDirectory]]URLByAppendingPathComponent:@"Stores"];

    NSFileManager *fileManager = [NSFileManager defaultManager];

    if (![fileManager fileExistsAtPath:[storesDirectory path]]) {
        NSError *error = nil;
        if ([fileManager createDirectoryAtURL:storesDirectory
                   withIntermediateDirectories:YES
                                    attributes:nil
                                         error:&error]) {
            //File created
        } else {

            //Error
        }
    }

    return storesDirectory;

}

- (NSURL *)storeURL {

    return [[self applicationStoresDirectory] URLByAppendingPathComponent:storeFileName];

}

#pragma mark - 
#pragma mark - SETUP
- (id)init {

    if (self = [super init]) {
        _model = [NSManagedObjectModel mergedModelFromBundles:nil];
        _coordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:_model];
        _context = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
        [_context setPersistentStoreCoordinator:_coordinator];
    }

    return self;
}

- (void)loadStore {

    if (_store) return; // Don't load store if it is already loaded

    // to generate the database in the app launching comment next lines...

    if(![self getFileExistence:storeFileName]){
        // file URL in our bundle
        NSURL *fileFromBundle = [[NSBundle mainBundle]URLForResource:@"FaultReporting" withExtension:@"sqlite"];

        // Destination URL
        NSURL *destinationURL = [[self applicationStoresDirectory] URLByAppendingPathComponent:@"FaultReporting.sqlite"];

        // copy it over
        [[NSFileManager defaultManager]copyItemAtURL:fileFromBundle toURL:destinationURL error:nil];
    }

    // end of comments

    NSError *error = nil;

    @try {
        _store = [_coordinator addPersistentStoreWithType:NSSQLiteStoreType
                                            configuration:nil
                                                      URL:[self storeURL]
                                                  options:@{                                                         NSMigratePersistentStoresAutomaticallyOption: @(YES),
                                                            NSInferMappingModelAutomaticallyOption: @(YES)}
                                                    error:&error];
    }
    @catch (NSException *exception) {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:[NSString stringWithFormat:@"Error: %@, %@",error, [error userInfo]] delegate:self
                                              cancelButtonTitle:@"OK"
                                              otherButtonTitles:nil, nil];
        [alert show];
    }
    @finally {
        //
    }

}

Answer 1

苏。不确定您是否这样做，但请尝试以下操作：

    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                             [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
                             [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];
[[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:self.managedObjectModel];
    NSError* error;
    [managedObjectContext.persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType
                                                                  configuration:nil
                                                                            URL:self.storeUrl
                                                                        options:options // this is required to migrate some core data model attributes
                                                                          error:&error];

基本上必须在设置时告诉它在选项中使用此迁移内容。