iCloud with MonoTouch

IntroductionThis session discusses Apple’s new iOS5 iCloudfunctionality and how to implement iCloud featureswith MonoTouch.We’ll cover:• iCloud Basics & Setup• iCloud Key-Value Storage• iCloud Document Storage• iCloud Backup (iOS Data Storage Guidelines) Xamarin Copyright 2012 © Xamarin Inc. All rights reserved

iCloud Basics (i) • Remote storage & backup • Synchronization of data across devices (iOS & Mac OS X) but NOT conﬂict resolution • OS process controls sending/receiving CloudiPhone Local storage storage Local storage iCloud Daemon iCloud Daemon iCloud Daemon Mac Local storage iPad

iCloud Basics (ii)• 4 ways to utilize iCloud: • Key-Value Pairs today’s topic • UIDocument • CoreData another • Individual ﬁles/folders time...

iCloud Setup (i)• App ID & Provisioning Proﬁle (developer.apple.com) • grants iCloud support (tick the box!) • linked to your TeamID and the BundleID• Entitlements.plist (in your project) • specify TeamID & BundleID • use these keys: com.apple.developer.ubiquity-kvstore-identifier com.apple.developer.ubiquity-container-identifiers

iCloud Setup (iii)• MonoDevelop Entitlements UI with placeholder expansion: • $(TeamPrefixIdentifier) automatically added • $(CFBundleIdentifier) for the default ubiquity-identifier han it E asier t ith l ooks, w lop! Mono Deve

iCloud Setup (iv)• Don’t forget the devices! • Same AppleID on each device

Key-Value Pairs (i)• Similar to NSUserDefaults• Simple types only (whatever works in a plist): text, number, date• Limited size: • 64Kb total • 64Kb max per key too• Recommendation: use NSUserDefaults and ‘shadow’ with iCloud Key-Value pairs

Key-Value Pairs (ii)Example creates a ‘key’ for each device, plus a Shared one.

Key-Value Pairs (iii)• SetString• GetString• Synchronize() returns false if no iCloud OR if no updates are required• Your app should run even if the Key-Values are empty! (sounds obvious, but...)

Key-Value Pairs (iv) • Change Notiﬁcations Register for notiﬁcationServerChangeInitialSyncChangeQuotaViolationChangeTells us which keys NSArray of IntPtrshave changed values Loop through the keys, get the new values and do something!

Files in the Cloud • NSFileCoordinator & NSFilePresenter work with the iCloud to prevent contention on the local copy • UIDocument hides that complexity from you! aka UbiquityContainer Cloud storage Presenter / Coordinator Local Presenter / Coordinator Local storage storageiPhone iCloud Daemon iCloud Daemon Mac Presenter / Coordinator iCloud Daemon or just use Local UIDocument! storage iPad

UbiquityContainer Ru ki Bloc backg a all! ng c round n on thread!• NSFileManager.DefaultManager.GetUrlForUbiquityContainer() • /private/var/mobile/Library/Mobile%20Documents/ AAA7MMJKYN~com~xamarin~samples~taskcloud/ Documents/ (user-visible in Settings) <your other stuff>• Not to be confused with your app’s home directory • /private/var/mobile/Applications/42871799- F2CD-455B-9353-749B15C8AA76/ TaskCloud.app (app bundle) Documents/ (user-visible in iTunes) Library/ <your other stuff>

UIDocument (spoilers)• Where are iCloud documents stored? UbiquityContainer Asyn c• How do you create a UIDoc? UIDoc.Save(ForCreating) Asyn c• How do you open one? UIDoc.Open() Asyn• How are changes applied? your model on the UIDoc) c (to• How do you save it again? UpdateChangeCount() UIDoc.• What if it changes elsewhere? for notiﬁcation... Listen Asyn c• How do you enumerate NSMetadataQuery() Asyn c UIDocs? Asyn c

UIDocument (example)

Finding UbiquityContainerThis one line iskey to getting Asyn ciCloud working! Do this in FinishedLoading. Apple also recommends re-checking each time the app comes to the foreground.

Subclassing UIDocument• Override the ‘read’ and ‘write’ methods: • Actually called LoadFromContents() and ContentsForType()• iCloud takes care of when they’re called and manages contention at the ﬁle system level.• You NEVER read/write the ﬁlesystem directly! • Save(CompletionHandler) As ync hro no • Open(CompletionHandler) us! • UpdateChangeCount

Subclassing UIDocument url to UbiquityContainer location default value‘Model’ can beas simple orcomplex as youlike aka ‘Open’So we can respond to this datachanges if we want aka ‘Save’ accesses the model and sends to ﬁlesystem

Create a UIDocPut user-generated ﬁles inthe /Documents/ directory Has the ‘(default text)’ setSave happens Asynasynchronously, the ccompletion handler runswhen it is done • You could also use NSFileManager.DefaultManager.SetUbiquitous() to move an existing ﬁle from your home directory to the UbiquityContainer

Open UIDoc Open speciﬁc ﬁlenamefrom the /Documents/ directory Asyn c Might need to be run on Main thread

Changes Applied & SavedUpdateChangeCount() is Update the model withall that is required to the edited textsignal to iCloud that theﬁle should be saved* * You can implement full undo/redo instead of UIDocumentChangeKind.Done

Changes ElsewhereListen for notification sent bythe UIDocument subclasswhen it is changed When that notificationoccurs, we are grabbing theupdated text and assigning it to the UITextView ** In a real app, you would probably want to do someconflict resolution instead...

Enumerate UIDocs (i)CloudUIDoc exampleLooking for a single,specific filename Special Predicate syntax(monkeyDocFilename)TaskCloud example (just to show a different query) Looking for all Special Predicate syntax *.task files queryDidFinishGathering on next slide...

Enumerate UIDocs (ii)When the NSMetadataQuery is done,we stop it (it could keep running/monitoring) and remove our listener We expect only one ﬁle in theexample app; get its “ItemURL” thencreate and open the document from that location • Metadata sync’s faster, so other devices will learn if a particular ﬁle has been created (even though they don’t know the contents)

Debugging Tips (i)• The /Documents/ directory can be managed by the user (and you, for testing)

Debugging Tips (ii) • Check your iCloud-linked Mac, sync’d ﬁles will be there if everything is working correctly/Users/<you>/Library/Mobile Documents/<TeamId><BundleId>/Documents

iOS Data StorageGuidelines (for iCloud)• Only documents that are user-generated should go into /Documents/• Data that can be re-created should go into /Library/Caches/• Temp data should be in /tmp/• Use the “do not backup” attribute to prevent ANY ﬁles being backed-up to iCloud

Other examples• Key-Value ~ chat2self

Other examples• UIDocument ~ TaskCloud

References (i)Introduction to iOS 5 (currently being updated)http://docs.xamarin.com/ios/tutorials/Introduction_to_iOS_5What’s New in iOShttps://developer.apple.com/library/ios/#releasenotes/General/WhatsNewIniPhoneOS/Introduction/Introduction.htmlTaskCloud - iCloud UIDocument samplehttp://conceptdev.blogspot.com.au/2012/03/icloud-uidocument-sample-taskcloud.htmlhttps://github.com/conceptdev/taskcloudchat2self - iCloud Key-Value samplehttp://conceptdev.blogspot.com.au/2012/02/icloud-key-value-example-chat2self.htmlhttps://github.com/conceptdev/Chat2selfiOS Data Storage Guidelineshttps://developer.apple.com/icloud/documentation/data-storage/ Xamarin Copyright 2012 © Xamarin Inc. All rights reserved

References (ii)NSFilePresenter Protocol Referencehttp://developer.apple.com/library/mac/#documentation/Foundation/Reference/NSFilePresenter_protocol/Reference/Reference.htmlNSFileCoordinator Class Referencehttp://developer.apple.com/library/mac/#documentation/Foundation/Reference/NSFileCoordinator_class/Reference/Reference.htmliCloud Developer Documentationhttps://developer.apple.com/icloud/documentation/ Xamarin Copyright 2012 © Xamarin Inc. All rights reserved

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iCloud with MonoTouch

by Xamarin on Mar 24, 2012

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