ios - 如何在我的无处不在的容器中获取所有可用的持久存储？

Question

在我的应用程序中，我有几个持久存储，用户可以删除和添加存储。我最近将 iCloud 添加到项目中，现在我需要知道哪些商店在启动时可用，以便我可以列出它们。以前，这是由我在创建和删除存储时管理的数组处理的。但现在可以创建或删除存储或单独的设备，我希望在我的无处不在的容器中获得所有可用的持久存储。这可能吗？

Answer 1

这是我用来查找新文件或已删除文件的代码。发布您的任何问题，我会尽力回复。

/*!  Creates and starts a metadata query for iCloud files

 */
- (void)createFileQuery {
    [_query stopQuery];

    if ([[CloudManager sharedManager] isCloudEnabled]) {
        if (_query) {
            [_query startQuery];
        }
        else {
            _query = [[NSMetadataQuery alloc] init];

            [_query setSearchScopes:[NSArray arrayWithObjects:NSMetadataQueryUbiquitousDocumentsScope, NSMetadataQueryUbiquitousDataScope, nil]];
            NSString *str = @"*";
            [_query setPredicate:[NSPredicate predicateWithFormat:@"%K LIKE %@", NSMetadataItemFSNameKey, str]];

            NSNotificationCenter* notificationCenter = [NSNotificationCenter defaultCenter];
            [notificationCenter addObserver:self selector:@selector(fileListReceived) name:NSMetadataQueryDidFinishGatheringNotification object:_query];
            [notificationCenter addObserver:self selector:@selector(fileListReceived) name:NSMetadataQueryDidUpdateNotification object:_query];
            [_query startQuery];
        }
    }

}

/*!  Gets called by the metadata query any time files change

 */
- (void)fileListReceived {
    //LOG(@"fileListReceived called.");

    bool found = NO;

    if ([self getNewiCloudDocs]) {
        //LOG(@"  New iCloud documents found!");
        found = YES;
    }

    if ([self getDeletediCloudDocs]) {
        //LOG(@"  Deleted iCloud documents found!");
        found = YES;
    }

    // Just check the local files again...
    if (found)
        [self updateList];

    return;

}

/*! Gets the list of files in the iCloud directory and compares against files we have locally
    and then creates new ones if required.  WARNING: files appear in iCloud before they appear
    locally when we are creating new documents so we must set a flag so we know to ignore any 
    new files that appear if we are busy creating a new document already.  Only applies if we
    have initiated creating a new document on this device!

    @return Returns true if any have been found
 */
- (bool)getNewiCloudDocs {
    //FLOG(@"getNewiCloudDocs called");
    bool found = NO;

    NSURL *iCloudDirectory = [[CloudManager sharedManager] iCloudCoreDataURL];

    //FLOG(@"  iCloudDirectory is %@", iCloudDirectory);

    // Get the top level directory names are these will represent all the iCloud documents
    NSArray* cloudDocuments = [[NSFileManager defaultManager] contentsOfDirectoryAtURL:iCloudDirectory includingPropertiesForKeys:nil options:0 error:nil];

    //Now get an array of the local document names including any UUID because we want then to be unique
    NSMutableArray *localFileIDs = [[NSMutableArray alloc] init];

    for (NSURL *doc in _localDocuments) {
        [localFileIDs addObject:[doc lastPathComponent]];
    }

    // Check if there are any we don't already have
    //FLOG(@"  iCloud Documents are:");
    for (NSURL* document in cloudDocuments) {
        //FLOG(@"   %@", [document lastPathComponent]);

        NSString *name = [document lastPathComponent];

        if (![localFileIDs containsObject:name]) {
            //FLOG(@"  new file found: %@", name);
            found = YES;
            [self createLocalCopyOfICloudFile: name];

        }
    }
    return found;
}
/*! Looks for files we have that are not in iCloud and are local.
    These have probably been deleted by some other device so remove them.

    @return Returns true if any have been found
 */
- (bool)getDeletediCloudDocs {
    //FLOG(@"getDeletediCloudDocs called");
    bool found = NO;

    NSURL *iCloudDirectory = [[CloudManager sharedManager] iCloudCoreDataURL];

    //Now get an array of the local document names including any UUID because we want then to be unique
    NSMutableArray *localFileIDs = [[NSMutableArray alloc] init];
    NSMutableArray *cloudFileIDs = [[NSMutableArray alloc] init];


    for (NSURL *doc in _localDocuments) {
        [localFileIDs addObject:[doc lastPathComponent]];
    }

    // Get the top level directory names are these will represent all the iCloud documents
    NSArray* cloudDocuments = [[NSFileManager defaultManager] contentsOfDirectoryAtURL:iCloudDirectory includingPropertiesForKeys:nil options:0 error:nil];
    if ([cloudDocuments count]) {

        //FLOG(@" %d documents found in iCloud", [cloudDocuments count]);
        //FLOG(@"   docs are: %@", cloudDocuments);
        for (NSURL* doc in cloudDocuments) {
            [cloudFileIDs addObject:[doc lastPathComponent]];
        }

        // Check if there are documents that we have that are not in iCloud
        //FLOG(@"  Deleted iCloud Documents are:");
        for (NSURL* document in _localDocuments) {
            NSString *name = [document lastPathComponent];

            if (![cloudFileIDs containsObject:name]) {
                FLOG(@"  REMOVED iCloud file detected: %@", name);
                found = YES;
                [self removeLocalCopyOfiCloudFile: name];

            }
        }
    } else {

        FLOG(@" no documents found in iCloud");
        FLOG(@" removing all local documents");

        for (NSURL* document in _localDocuments) {
            NSString *name = [document lastPathComponent];
            //FLOG(@"  removing local file %@", name);
            found = YES;
            [self removeLocalCopyOfiCloudFile: name];
        }

    }

    return found;
}

- (void)createLocalCopyOfICloudFile:(NSString *)fileName {

    if (!_creatingDocument) {
        NSURL* fileURL = [[[CloudManager sharedManager] documentsDirectoryURL] URLByAppendingPathComponent:fileName];

        [self.appDelegate createLocalCopyOfCloudFile:fileURL];
    } else {
        LOG(@"Busy creating document so don't do anything!");
    }
}

- (void)removeLocalFile:(NSString *)fileName {
    LOG(@"");
    FLOG(@"  REMOVING local copy of file: %@", fileName);
    NSURL* fileURL = [[[CloudManager sharedManager] documentsDirectoryURL] URLByAppendingPathComponent:fileName];
    [self deleteDocumentAtURL:fileURL];
    LOG(@"");
}

- (void)removeLocalCopyOfiCloudFile:(NSString *)fileName {
    LOG(@"");
    if (!_deletingDocument) {
        FLOG(@"  REMOVING local copy of DELETED iCloud file: %@", fileName);
        NSURL* fileURL = [[[CloudManager sharedManager] documentsDirectoryURL] URLByAppendingPathComponent:fileName];
        [self deleteLocalCopyOfiCloudDocumentAtURL:fileURL];
        LOG(@"");
    } else {
        LOG(@"Busy deleting document so don't do anything!");
    }
}