iCloud Document Storage with UIDocument - Beginning iOS Cloud and Database Development - page 102

[[NSNotificationCenter defaultCenter] removeObserver:self
name:NSMetadataQueryDidUpdateNotification object:nil];
[_query stopQuery];
_query = nil;
}
}
The queryiCloud method starts out by calling our stopiCloudQuery method which does exactly that.
We will go into more detail on how it does that shortly. Then we call our documentQuery method that
we just created and assign the return value to our private _query property. But, we haven't created
that so let's do that now. In the private interface add this line:
@property (strong) NSMetadataQuery *query;
Now that we have our query property created and assigned let's move on. In the next two lines we
add our self as an observer for two messages that will be fired by our NSMetadataQuery . They are
NSMetadataQueryDidDidFinishGatheringNotification and NSMetadataQueryDidUpdateNotification .
We tell notification center that when these messages or notifications are fired we want to call our
processiCloudFiles: method. We will write that shortly. We end our method call by calling the
startQuery method on our NSMetadataQuery object.
Our stopiCloudQuery method is similar. We first check to see if query is not nil. If it is, then we
remove ourselves as the observer for both of the messages we subscribed to earlier. Then we call
stopQuery on our NSMetadataQuey object and finally set our object to nil.
Before we can write our processiCloudFiles: method we need to add a few more private properties.
In the private interface add the following:
@property (strong) NSMutableArray *iCloudURLs;
@property BOOL iCloudIsReady;
@property BOOL awaitingMoveLocalToiCloud;
@property BOOL awaitingCopyiCloudToLocal;
Let's also not forget to initialize the iCloudURLs array. In your viewDidLoad: add an initialization for
iCloudURLs just above the line where you initialize your entries array.
_iCloudURLs = [NSMutableArray array];
Now we can write our processiCloudFiles : method.
-(void)processiCloudFiles:(NSNotification *)notification {
[_query disableUpdates];
[_iCloudURLs removeAllObjects];
[[_query results] enumerateObjectsUsingBlock:^(NSMetadataItem *item,
NSUInteger idx, BOOL *stop) {
NSURL *fileURL = [item valueForAttribute:NSMetadataItemURLKey];
NSNumber *aBool = nil;