How to Sync an NSDocument from iPad/iPhone to Mac osx with iCloud

Question

How to Sync an nsdocument from ipad/iphone to Mac osx with icloud

I managed to get it working! from Mac osx to iPhone/iPad but not from iPad/iPhone to Mac osx

Here's my code from the subclassed nsdocument file on osx:

Header file:

#import <Cocoa/Cocoa.h>
#import <Foundation/Foundation.h>

@interface subclassedNSDocument : NSDocument

@property (strong) NSData *myData;

@end

Implementation file:

- (BOOL)readFromData:(NSData *)data ofType:(NSString *)typeName error:(NSError **)outError 
{
    BOOL readSuccess = NO;
    if (data) 
    {
        readSuccess = YES;
        [self setMyData:data];
    }

    [[NSNotificationCenter defaultCenter] postNotificationName:@"dataModified" 
                                                        object:self];

    return readSuccess;
}

- (NSData *)dataOfType:(NSString *)typeName error:(NSError **)outError 
{
    if (!myData && outError) {
        *outError = [NSError errorWithDomain:NSCocoaErrorDomain
                                        code:NSFileWriteUnknownError userInfo:nil];
    }
    return myData;
}

and in the AppDelegate.m file:

#define kFILENAME @"mydocument.dox"

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    NSURL *ubiq = [[NSFileManager defaultManager] 
                   URLForUbiquityContainerIdentifier:nil];
    if (ubiq) {
        NSLog(@"iCloud access at %@", ubiq);
        // TODO: Load document... 
        [self loadDocument];
    }
    else 
    {
        NSLog(@"No iCloud access");
    }

    [[NSNotificationCenter defaultCenter] addObserver:self 
                                             selector:@selector(dataReloaded:) 
                                                 name:@"dataModified" object:nil];
}

- (void)update_iCloud
{
    NSURL *ubiq = [[NSFileManager defaultManager] URLForUbiquityContainerIdentifier:nil];
    NSURL *ubiquitousPackage = [[ubiq URLByAppendingPathComponent:@"Documents"] URLByAppendingPathComponent:kFILENAME];
    self.doc.myData = [NSKeyedArchiver archivedDataWithRootObject:[@"Your Data Array or any data", nil]];
    [self.doc saveToURL:ubiquitousPackage ofType:@"dox" forSaveOperation:NSSaveOperation error:nil];
}

- (void)loadData:(NSMetadataQuery *)query {

    if ([query resultCount] == 1) {

        NSMetadataItem *item = [query resultAtIndex:0];
        NSURL *url = [item valueForAttribute:NSMetadataItemURLKey];
        NSLog(@"url = %@",url);
        subclassedNSDocument *doc = [[subclassedNSDocument alloc] initWithContentsOfURL:url ofType:@"dox" error:nil];
        [doc setFileURL:url];
        self.doc = doc;
    } 
    else {

        NSURL *ubiq = [[NSFileManager defaultManager] URLForUbiquityContainerIdentifier:nil];
        NSURL *ubiquitousPackage = [[ubiq URLByAppendingPathComponent:@"Documents"] URLByAppendingPathComponent:kFILENAME];

        dataUrls *doc = [[dataUrls alloc] init];
        [self.doc setFileURL:ubiquitousPackage];
        self.doc = doc;
        [self.doc saveToURL:ubiquitousPackage ofType:@"dox" forSaveOperation:NSSaveOperation error:nil];
    }

}

- (void)queryDidFinishGathering:(NSNotification *)notification {

    NSMetadataQuery *query = [notification object];
    [query disableUpdates];
    [query stopQuery];

    [[NSNotificationCenter defaultCenter] removeObserver:self 
                                                    name:NSMetadataQueryDidFinishGatheringNotification
                                                  object:query];

    _query = nil;

    [self loadData:query];

}

- (void)loadDocument {

    NSMetadataQuery *query = [[NSMetadataQuery alloc] init];
    _query = query;
    [query setSearchScopes:[NSArray arrayWithObject:NSMetadataQueryUbiquitousDocumentsScope]];
    NSPredicate *pred = [NSPredicate predicateWithFormat: @"%K == %@", NSMetadataItemFSNameKey, kFILENAME];
    [query setPredicate:pred];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(queryDidFinishGathering:) name:NSMetadataQueryDidFinishGatheringNotification object:query];

    [query startQuery];

}

- (void)dataReloaded:(NSNotification *)notification 
{
    self.doc = notification.object;

    NSArray *arrFromCloud = [NSKeyedUnarchiver unarchiveObjectWithData:self.doc.myData];

    //Update you UI with new data
}

The question is: The only thing that I haven't got working is that if I change the data of the document on the iPad, the Mac app doesn't call the readFromData method for to update from iCloud, does anyone know what I am missing?

On iOS, the equivalent method, loadFromContents, is called automatically on every change of the UIDocument in iCloud. On OS X the readFromData is called once on load but never called again.

Hope my code can help, for me it is working one way from Mac to iPad.

Answer 1

Fixed it myself.

Apparently it's just a poorly implemented and over-complicated sample code.

On applicationDidFinishLaunching: we just need

_query = [[NSMetadataQuery alloc] init];
[_query setSearchScopes:[NSArray arrayWithObject:NSMetadataQueryUbiquitousDocumentsScope]];
NSPredicate *pred = [NSPredicate predicateWithFormat: @"%K == %@", NSMetadataItemFSNameKey, kFILENAME];
[_query setPredicate:pred];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(queryUpdated:) name:NSMetadataQueryDidUpdateNotification object:_query];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(queryUpdated:) name:NSMetadataQueryDidFinishGatheringNotification object:_query];
[_query startQuery];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(dataReloaded:) name:@"dataModified" object:nil];

And add the following method:

- (void)queryUpdated:(NSNotification *)notification {
    NSLog(@"queryUpdated called...");
    NSMetadataQuery *query = [notification object];
    [query disableUpdates];

    if ([query resultCount] == 1) {
        // update views, etc. here
    }

    [query enableUpdates];
}

Then remove all the uncalled methods from the original sample.