我正在将 iCloud 添加到现有应用程序。同步工作正常，但我需要排除一些实体，或者想出一个解决方法，因为我的一些核心数据正在被复制。

例如:

CertificateColour 被发送到 TableView ，现在每行显示两次。

CertificateType 在操作表中显示四个选项，现在有 8 行，每行已复制一次。

我正在使用 https://github.com/mluisbrown/iCloudCoreDataStack用于我的核心数据同步。

我 checkout Core data + iCloud: exclude certain attributes from sync?这表明了一些事情:
1. 创建一个单独的本地和云存储，听起来......很有前途但不确定如何，因为这是我第一次尝试使用 iCloud 和核心数据。
2. 第二个建议是同步到一个包含唯一设备标识符的实体，但这已被弃用，并且再次不确定核心数据的过程

AppDelegate.h

#import <UIKit/UIKit.h>
#import <sqlite3.h>
#import "PersistentStack.h"

@interface ICAppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;
@property (strong, nonatomic) UINavigationController *navigationController;

@property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
@property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel;
@property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator;

- (void)saveContext;
- (NSURL *)applicationDocumentsDirectory;

@end

Appdelegate.m

@interface ICAppDelegate () <DBSessionDelegate, DBNetworkRequestDelegate>

//iCloud
@property (nonatomic, strong) PersistentStack* persistentStack;
@property (nonatomic, strong) NSManagedObjectContext* managedObjectContext;

@end

@implementation ICAppDelegate

@synthesize window = _window;
@synthesize navigationController = _navigationController;
@synthesize managedObjectContext = __managedObjectContext;
@synthesize managedObjectModel = __managedObjectModel;
@synthesize persistentStoreCoordinator = __persistentStoreCoordinator;



- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{

    //iCloud
    self.persistentStack = [[PersistentStack alloc] initWithStoreURL:self.storeURL modelURL:self.modelURL];
    self.managedObjectContext = self.persistentStack.managedObjectContext;



    BOOL populateData = NO;
    BOOL copyDb = YES;

    // Copy DB to documents directory
    if (copyDb == YES) {

        NSString *srcPath = [[NSBundle mainBundle] pathForResource:@"myApp" ofType:@"sqlite"];
        NSString *destPath = [[NSHomeDirectory() stringByAppendingPathComponent:@"Documents"] stringByAppendingPathComponent:@"myApp.sqlite"];

        if (![[NSFileManager defaultManager] fileExistsAtPath:srcPath]) {
            DebugLog(@"Source file doesn't exist");
        }
        if (![[NSFileManager defaultManager] fileExistsAtPath:destPath]) {
            DebugLog(@"Copying DB to documents directory");
            NSError *error = nil;
            [[NSFileManager defaultManager] copyItemAtPath:srcPath toPath:destPath error:&error];
            if (error != nil) {
                DebugLog(@"Copy failed %@", [error localizedDescription]);
            }
        }
    }


    /////*****ALL OF THIS IS DUPLICATED AND NEEDS EXCLUDING FROM ICLOUD BACK UP****////////////

        if (populateData) {

        DebugLog(@"Populating database");
        NSManagedObjectContext *context = [self managedObjectContext];

        Subscription *subscription = (Subscription *)[NSEntityDescription insertNewObjectForEntityForName:@"Subscription" inManagedObjectContext:context];
        subscription.subscribed = @NO;

        CertificateColour *red = (CertificateColour *)[NSEntityDescription insertNewObjectForEntityForName:@"CertificateColour" inManagedObjectContext:context];
        red.name = @"Red";
        red.redComponent = @1.0f;
        red.greenComponent = @0.0f;
        red.blueComponent = @0.0f;

        CertificateColour *purple = (CertificateColour *)[NSEntityDescription insertNewObjectForEntityForName:@"CertificateColour" inManagedObjectContext:context];
        purple.name = @"Purple";
        purple.redComponent = @0.4f;
        purple.greenComponent = @0.0f;
        purple.blueComponent = @0.6f;

        CertificateColour *green = (CertificateColour *)[NSEntityDescription insertNewObjectForEntityForName:@"CertificateColour" inManagedObjectContext:context];
        green.name = @"Green";
        green.redComponent = @0.0f;
        green.greenComponent = @0.6f;
        green.blueComponent = @0.2f;

        CertificateColour *blue = (CertificateColour *)[NSEntityDescription insertNewObjectForEntityForName:@"CertificateColour" inManagedObjectContext:context];
        blue.name = @"Blue";
        blue.redComponent = @0.0f;
        blue.greenComponent = @0.2f;
        blue.blueComponent = @1.0f;


        ICCertificateTypeManager *ctm = [ICCertificateTypeManager manager];

        CertificateType *type = [ctm newCertificateType];
        type.title = @"Works";
        type.identifier = @(Works);

        type = [ctm newCertificateType];
        type.title = @"Type1";
        type.identifier = @(Type1);

        type = [ctm newCertificateType];
        type.title = @"Type2";
        type.identifier = @(Type2);

        type = [ctm newCertificateType];
        type.title = @"Type4";
        type.identifier = @(Type3);

        [self saveContext];
    }

       if ([[ICWebServiceClient sharedInstance] isLoggedIn])
    {
        DebugLog(@"User is logged in ");
    }
    ////////////////////////////////////////////////////////////


    return YES;
}

- (BOOL)application:(UIApplication *)application handleOpenURL:(NSURL *)url {
    LogCmd();
    if ([[DBSession sharedSession] handleOpenURL:url]) {
        if ([[DBSession sharedSession] isLinked]) {
            DebugLog(@"handling url");
        }
        return YES;
    }

    return NO;
}

- (void)applicationWillResignActive:(UIApplication *)application
{

}

- (void)applicationDidEnterBackground:(UIApplication *)application
{

    [self.managedObjectContext save:NULL];
}

- (void)applicationWillEnterForeground:(UIApplication *)application
{

}

- (void)applicationDidBecomeActive:(UIApplication *)application
{

}

- (void)applicationWillTerminate:(UIApplication *)application
{

    [self saveContext];
}

- (void)saveContext
{
    NSError *error = nil;
    NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
    if (managedObjectContext != nil) {
        if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {


            NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
            abort();
        } 
    }
}


#pragma mark - DBSessionDelegate

- (void)sessionDidReceiveAuthorizationFailure:(DBSession*)session userId:(NSString *)userId
{
    LogCmd();
}

#pragma mark - DBNetworkRequestDelegate

static int outstandingRequests;

- (void)networkRequestStarted {
    outstandingRequests++;
    if (outstandingRequests == 1) {
        [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
    }
}

- (void)networkRequestStopped {
    outstandingRequests--;
    if (outstandingRequests == 0) {
        [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];
    }
}


#pragma mark - Core Data stack

// Returns the managed object context for the application.
// If the context doesn't already exist, it is created and bound to the persistent store coordinator for the application.
- (NSManagedObjectContext *)managedObjectContext
{
    if (__managedObjectContext != nil) {
        return __managedObjectContext;
    }

    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
    if (coordinator != nil) {
        __managedObjectContext = [[NSManagedObjectContext alloc] init];
        [__managedObjectContext setPersistentStoreCoordinator:coordinator];
    }
    return __managedObjectContext;
}

// Returns the managed object model for the application.
// If the model doesn't already exist, it is created from the application's model.
- (NSManagedObjectModel *)managedObjectModel
{
    if (__managedObjectModel != nil) {
        return __managedObjectModel;
    }
    NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"myApp" withExtension:@"momd"];
    __managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
    return __managedObjectModel;
}

// Returns the persistent store coordinator for the application.
// If the coordinator doesn't already exist, it is created and the application's store added to it.
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
    if (__persistentStoreCoordinator != nil) {
        return __persistentStoreCoordinator;
    }

    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"myApp.sqlite"];

    NSError *error = nil;
    __persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
    if (![__persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {





        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }    

    return __persistentStoreCoordinator;
}

#pragma mark - Application's Documents directory

// Returns the URL to the application's Documents directory.
- (NSURL *)applicationDocumentsDirectory
{
    return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}


#pragma mark - iCloud store

- (NSURL*)storeURL
{
    NSURL* documentsDirectory = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:YES error:NULL];
    return [documentsDirectory URLByAppendingPathComponent:@"myApp.sqlite"];
}

- (NSURL*)modelURL
{
    return [[NSBundle mainBundle] URLForResource:@"myApp" withExtension:@"momd"];
}


@end

最佳答案

使用多个持久存储确实是从 iCloud 中排除特定实体类型的唯一选择。为此，您可以在同一个持久存储协调器上多次调用 addPersistentStoreWithType 但使用不同的持久存储文件(之所以称为协调器，是因为它可以在多个持久存储之间进行协调)。为其中一家商店使用 iCloud 选项，但不为另一家商店使用。

您可以使用具有不同实体的两个单独的托管对象模型，也可以使用具有不同配置选项的单个模型。两者都有效。

您可能遇到的问题是您无法在不同持久存储文件中的实例之间创建关系。 (从技术上讲，您可以创建它们，只是无法保存它们，这在大多数情况下使它们毫无用处)。您的 CertificateType 实体听起来像是与其他实例有关系，但这不适用于多个商店。

您可以做的是同步每个对象，但添加代码来检测重复项并进行处理。在 Apple 的“SharedCoreData”示例应用程序中有一个很好的例子，来自 WWDC 2012 的“使用 iCloud 和核心数据” session ，但我现在无法在网上找到它的副本。你会做类似的事情

1. 等待 NSPersistentStoreDidImportUbiquitousContentChangesNotification
2. 当它到达时，查看通知的 userInfo 以查看是否包含任何 CertificateType 对象。
3. 如果是，则对该实体进行提取以查找并匹配重复项
4. 以对您的应用有意义的任何方式清除这些重复项。

更新:我忘了我做了一个 blog post which covers this in more detail .我还找到了 WWDC 2012 sample code bundle 的链接(链接需要当前的开发者帐户)，其中包括 SharedCoreData。该演示中的很多内容都已过时，但重复删除代码仍然有效。

关于ios - 与 iCloud 同步核心数据 - 不包括实体，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/22834654/