如何为 Core Data (iOS7) 添加启用和禁用 iCloud 同步的选项？

以下是我的想法/尝试:

要禁用 iCloud 同步:

NSDictionary *options = @{NSPersistentStoreUbiquitousContentNameKey: @"MYStore"};
[NSPersistentStoreCoordinator removeUbiquitousContentAndPersistentStoreAtURL:storeUrl options:options error:&error];

但是，我认为这可能会删除 iCloud 中的所有数据？我不想这样。

启用 iCloud 同步:

NSDictionary *options = @{NSPersistentStoreUbiquitousContentNameKey: @"MYStore"};
[__persistentStoreCoordinator lock];
result = [__persistentStoreCoordinator migratePersistentStore:result toURL:storeUrl options:options withType:NSSQLiteStoreType error:&error];
[__persistentStoreCoordinator unlock];

在这段代码中，我尝试使用 NSPersistentStoreUbiquitousContentNameKey 键添加选项，以便它开始与 iCloud 同步。但是，我不想将商店搬到新的位置。这段代码正确吗？

如何在应用程序运行时启用/禁用 iCloud？

最佳答案

以下是我用来启用或禁用 iCloud 同步 (OS X) 的方法，基本上每次都会重建商店，这与在应用程序运行时启用和禁用 iCloud 同步不同。所以你不想用它来“暂停”同步。

据我了解，您需要如下内容:

如果您在应用程序运行时关闭 iCloud 同步然后执行一些更新，您不希望同步这些更改，但稍后当您重新打开 iCloud 同步时您希望同步后续更改。

我可能是错的，但我认为您使用标准的 Core Data/iCloud 集成可能不太走运。

根据您的要求，也许您可​​以只观察导入通知并放弃任何更改 - 但我不明白您如何不会以可能导致后续导入失败的各种数据不一致而告终。

    // Removes the current Document from iCloud and deletes the local copy.
    // There does not appear to be any way of only removing ubiquitous content
    // and turning off iCloud sync.
    // So before we remove it we make a local copy by appending "_Backup" to the filename
    // (we should check this filename does not already exist and add a counter or something)
    //
    - (void)removeMeFromICloud {
        //LOG(@"removeMeFromICloud called");
        NSError *error;

        NSURL *currentURL = self.fileURL;
        NSString *fileType = self.fileType;
        NSString *extension = [currentURL pathExtension];
        NSString *path = [[currentURL URLByDeletingPathExtension] path];
        NSString *backupFilename = [NSString stringWithFormat:@"%@_Backup", path];
        NSURL *backupFileURL = [[[NSURL alloc] initFileURLWithPath:backupFilename] URLByAppendingPathExtension:extension];

        // We only have one store
        NSPersistentStore *currentStore = [self.managedObjectContext.persistentStoreCoordinator.persistentStores objectAtIndex:0];
        NSDictionary *currentOptions = currentStore.options;

        if ([self buildNewStoreAtURL:backupFileURL type:fileType error:&error]) {

            //FLOG(@" reset the moc...");
            [self.managedObjectContext reset];
            [self.managedObjectContext save:&error];

            //Set the document title
            //FLOG(@" current displayName is %@", self.displayName);
            self.fileURL = backupFileURL;

            //set the file extension hidden attribute to YES
            NSDictionary* fileAttrs = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES]
                                                                  forKey:NSFileExtensionHidden];
            if(![[NSFileManager defaultManager] setAttributes:fileAttrs
                                                 ofItemAtPath:[backupFileURL path]
                                                        error:&error])
                FLOG(@" unable to set file attributes to hide extension");

            // Now remove the old one
            bool success = [NSPersistentStoreCoordinator removeUbiquitousContentAndPersistentStoreAtURL:currentURL options:currentOptions error:&error];

            if (success) {
                FLOG(@" removed document from iCloud");
                FLOG(@" using backup copy");
            }
            else  {
                FLOG(@" error removing document from iCloud");
                FLOG(@" error is %@, %@", error, error.userInfo);
            }
        } else {
            FLOG(@" error creating backup before removing from iCloud");
            FLOG(@" error is %@, %@", error, error.userInfo);
        }
    }

    // in order to migrate to the cloud we have to build the database from scratch,
    // we can't just open it with iCloud parameters because we have to ensure that
    // log files get generated in iCloud that will allow the store to be rebuilt from
    // scratch by peer devices.
    //
    - (void)migrateMeToICloud {
        //LOG(@"migrateMeToICloud called");

        NSPersistentStoreCoordinator *psc = self.managedObjectContext.persistentStoreCoordinator;

        NSArray *stores = psc.persistentStores;
        NSError *error;

        // Now get current URL and add_iCloud to the document name, use this for the new store name
        NSURL *currentURL = self.fileURL;
        NSString *extension = [self.fileURL pathExtension];
        NSString *currentFilePathName = [[currentURL URLByDeletingPathExtension] path];
        NSString *uuidString = [[NSUUID UUID] UUIDString];
        NSString *newFilePathName = [NSString stringWithFormat:@"%@_UUID_%@",currentFilePathName, uuidString];

        // We must make it NSSQLite so get the right extension...
        NSURL *newURL = [[[NSURL alloc] initFileURLWithPath:newFilePathName] URLByAppendingPathExtension:extension];

        NSDictionary *options = [self storeOptionsForICloud:self.fileURL];
        NSString *ubiquityName = [options valueForKey:NSPersistentStoreUbiquitousContentNameKey];


        if ([stores count]) {
            NSPersistentStore *store = [stores objectAtIndex:0];

            if (store) {
                //FLOG(@" starting migration...");

                NSPersistentStore *newStore = [psc migratePersistentStore:store toURL:newURL options:options withType:NSSQLiteStoreType error:&error];
                //FLOG(@"  psc is %@", psc);

                //FLOG(@" done migrating...");
                if (newStore != nil) {
                    //FLOG(@" new store seems OK...");

                    // Set custom metadata so we know if it is synced in iCloud next time we open it
                    [self setiCloudMetaDataForStore:currentURL ofType:NSSQLiteStoreType iCloud:YES ubiquityName:ubiquityName];

                }
                else  {
                    FLOG(@" error migrating store");
                    FLOG(@" error is %@, %@", error, error.userInfo);

                }
            } else  {
                FLOG(@" store is nil, nothing to migrate!");
            }
        }

    }

// File is NEVER iCloud enabled when we do this.
// Is we do Save As we pnly build a local store wihout iCloud sync.
// User can select iCloud sync once Save As is done
//
- (bool)buildNewStoreAtURL:(NSURL*)newURL type:(NSString *)typeName error:(NSError **)error {

    //FLOG(@"buildNewStoreAtURL:type: called");

    NSError *myError;

    // We only have one store
    NSPersistentStore *currentStore = [self.managedObjectContext.persistentStoreCoordinator.persistentStores objectAtIndex:0];
    NSDictionary *currentOptions = currentStore.options;

    // We usually would need to create a new UUID for the new document if it is in iCloud.
    // But since we create a local copy only we don't need this.
    NSMutableDictionary *newOptions = [[NSMutableDictionary alloc] initWithDictionary:currentOptions];
    [newOptions setObject:@"DELETE" forKey:@"JOURNAL"];

    // Remove any iCloud options (this one includes the unique iCloud UUID
    [newOptions removeObjectForKey:NSPersistentStoreUbiquitousContentNameKey];

    // Remove Core Data ubiquity metadata
    [newOptions setObject:[NSNumber numberWithBool:YES] forKey:NSPersistentStoreRemoveUbiquitousMetadataOption];


    NSPersistentStoreCoordinator *psc = self.managedObjectContext.persistentStoreCoordinator;

    // Now migrate the store to the new location
    NSPersistentStore *newStore = [psc migratePersistentStore:currentStore toURL:newURL options:newOptions withType:typeName error:&myError];

    if (newStore) {

        // Now set up our custom metadata so we can determine if it has been synced in iCloud next time we open it
        NSDictionary *dict = [self getiCloudMetaDataForStore:[psc metadataForPersistentStore:newStore] iCloud:NO ubiquityName:nil];

        [psc setMetadata:dict forPersistentStore:newStore];

        return YES;
    }
    else {

        FLOG(@" problem creating new document");
        FLOG(@"  - error is %@, %@", myError, myError.userInfo);
        *error = myError;
        return NO;
    }

}

关于ios - 在应用程序运行时启用/禁用核心数据的 iCloud 同步，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/20022775/