My app is setup to receive CloudKit remote notifications. Sometimes it receives these notifications while it is running in the background. I have not done anything with these notifications yet - I have simply passed UIBackgroundFetchResultNewData to the completion handler. The reason is that I didn't think I could simply download from CloudKit while in the background - I thought that could only be done via Background Fetch or setting up a special job to run in the background. But I am revisiting this now, and I see that running the CKFetchRecordsOperation and downloading the related CKAsset file while in UIApplicationStateBackground actually does seem to work.
So my current code is this:
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler {
__ENTERING_METHOD__
CKNotification *ckNotification = [CKNotification notificationFromRemoteNotificationDictionary:userInfo];
if (ckNotification) {
if ([ckNotification.subscriptionID isEqualToString:kCKDocumentChangeSubscription]) {
CKRecordID *recordID = [(CKQueryNotification*)ckNotification recordID];
if (recordID) {
if([UIApplication sharedApplication].applicationState == UIApplicationStateBackground) {
if (completionHandler) {
completionHandler(UIBackgroundFetchResultNewData);
}
}
else {
CKFetchRecordsOperation *fetchRecordsOperation = [[CKFetchRecordsOperation alloc] initWithRecordIDs:@[recordID]];
fetchRecordsOperation.fetchRecordsCompletionBlock = ^(NSDictionary *recordsByRecordID, NSError *error) {
if (error) {
dispatch_async(dispatch_get_main_queue(), ^{
if (completionHandler) {
completionHandler(UIBackgroundFetchResultFailed);
}
});
}
else {
CKRecord *ckDocumentRecord = recordsByRecordID[recordID];
CKAsset *documentAsset = [ckDocumentRecord objectForKey:ckDocumentAsset];
NSData *data = [NSData dataWithContentsOfURL:documentAsset.fileURL];
[self handleData:data];
UIBackgroundFetchResult result = (data == nil)?UIBackgroundFetchResultFailed:UIBackgroundFetchResultNewData;
if (completion) {
completion(result);
}
}
};
CKContainer *defaultContainer = [CKContainer defaultContainer];
CKDatabase *publicDatabase = [defaultContainer publicCloudDatabase];
[publicDatabase addOperation:fetchRecordsOperation];
}
}
else {
if (completionHandler) {
completionHandler(UIBackgroundFetchResultFailed);
}
}
}
else {
if (completionHandler) {
completionHandler(UIBackgroundFetchResultNoData);
}
}
}
else {
if (completionHandler) {
completionHandler(UIBackgroundFetchResultNoData);
}
}
}
And I want this code to be this:
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler {
__ENTERING_METHOD__
CKNotification *ckNotification = [CKNotification notificationFromRemoteNotificationDictionary:userInfo];
if (ckNotification) {
if ([ckNotification.subscriptionID isEqualToString:kCKDocumentChangeSubscription]) {
CKRecordID *recordID = [(CKQueryNotification*)ckNotification recordID];
if (recordID) {
CKFetchRecordsOperation *fetchRecordsOperation = [[CKFetchRecordsOperation alloc] initWithRecordIDs:@[recordID]];
fetchRecordsOperation.fetchRecordsCompletionBlock = ^(NSDictionary *recordsByRecordID, NSError *error) {
if (error) {
dispatch_async(dispatch_get_main_queue(), ^{
if (completionHandler) {
completionHandler(UIBackgroundFetchResultFailed);
}
});
}
else {
CKRecord *ckDocumentRecord = recordsByRecordID[recordID];
CKAsset *documentAsset = [ckDocumentRecord objectForKey:ckDocumentAsset];
NSData *data = [NSData dataWithContentsOfURL:documentAsset.fileURL];
[self handleData:data];
UIBackgroundFetchResult result = (data == nil)?UIBackgroundFetchResultFailed:UIBackgroundFetchResultNewData;
if (completion) {
completion(result);
}
}
};
CKContainer *defaultContainer = [CKContainer defaultContainer];
CKDatabase *publicDatabase = [defaultContainer publicCloudDatabase];
[publicDatabase addOperation:fetchRecordsOperation];
}
else {
if (completionHandler) {
completionHandler(UIBackgroundFetchResultFailed);
}
}
}
else {
if (completionHandler) {
completionHandler(UIBackgroundFetchResultNoData);
}
}
}
else {
if (completionHandler) {
completionHandler(UIBackgroundFetchResultNoData);
}
}
}
Does running a CKFetchRecordsOperation and downloading the related CKAsset file while in the background constitute any sort of a violation of what can (or SHOULD) be done in the background?