iCloud Document Storage with UIDocument - Beginning iOS Cloud and Database Development - page 106

} else {
if(!_awaitingCopyiCloudToLocal){
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Turning iCloud Off"
message:@"What would you like to do with the documents currently on iCloud?" delegate:self
cancelButtonTitle:@"Keep Using iCloud" otherButtonTitles:@"Keep a local copy",@"Keep only on
iCloud", nil];
[alert setTag:3];
[alert show];
}
}
}
The start of this method is very similar to the previous one. We first check to see if we are
awaitingCopyiCloudToLocal and iCloudIsReady . If it is, then we start the copy process, however
if it isn't, we check to see whether _awaitingCopyiCloudToLocal is set to NO . If it is, then we create
an alertView and ask the user if they would like to keep using iCloud, Keep a local copy, or Keep
a copy only on iCloud. We set the tag of this alert to 3 so we can handle it correctly and then call
show.
If we are going to copy the iCloud files to our local directory, we first set our
_awaitingCopyiCloudToLocal BOOl value to NO . Then we enumerate through our iCloudURLs array.
We then use the same method we used in the previous method to get our destinationURL except
this time we pass YES for the last parameter.
We then create a block that will run on the background thread by calling dispatch_async .
We create an NSFileCoordinator and call the method coordinateReadingItemAtURL:op
tions:error:byAccessor: method. We pass in the iCloud URL and pass it an option of
NSFileCoordinatorReadingWithoutChanges . In our byAccessor: block we create an NSFileManager
object and then call copyItemAtURL:toURL:error: . Finally, we call the loadDocumentAtFileURL
method passing our destinationURL.
Now let's go modify our alertView to handle this new alert dialog.
} else if(alertView.tag == 3){
if(buttonIndex == alertView.cancelButtonIndex){
[self setiCloudOn:YES];
[self reload];
} else if(buttonIndex == alertView.firstOtherButtonIndex){
_awaitingCopyiCloudToLocal = YES;
if(_iCloudIsReady){
[self copyiCloudToLocal];
}
}
}
Here we check to see if the user selected “Keep using iCloud.” If they did, we set iCloudOn
and then call reload . Next we see if they selected “Keep a local copy.” If they did we set our
_awaitingCopyiCloudToLocal to YES. If iCloud is ready then we call copyiCloudToLocal . The final
selection “Keep only on iCloud” is an action we don't need to worry about because there data is
already on iCloud.