Watchkit Communication

Video of the talk is available at https://vimeo.com/119606531

The Watchkit architecture makes for some interesting challenges regarding getting data out of your main app and onto the watch. This covers the architectural and lifecycle basics before diving into the methods we have available to move data around to the watch.

Transcript

1. Curtis Herbert (.com) @parrots WatchKit Communication
2. What can we do in early 2015? Glance Notification App https://developer.apple.com/watchkit/
3. What can we do in early 2015? Glance Notification App https://developer.apple.com/watchkit/ You can provide users with timely read-only information that they care about with a Glance — a quick and lightweight view of your app.
4. What can we do in early 2015? Glance Notification App https://developer.apple.com/watchkit/ Actionable notifications built and designed with WatchKit let users take action right from their wrists.
5. What can we do in early 2015? Glance Notification App https://developer.apple.com/watchkit/ Your app on Apple Watch contains a full user interface. Users can launch, control, and interact with your app in ways unique to Apple Watch.
6. What Makes Up a WatchKit App?
7. Parent App Delivered with your app
8. Parent App E Watch Extension Delivered with your app
9. Parent App E Watch Extension Just the UI Watch “App” Delivered with your app
10. Parent App E Watch Extension Just the UI Watch “App” Delivered with your app
14. Parent App E Watch Extension Separate processes
15. Parent App E Watch Extension Separate processes
16. Parent App E Watch Extension setters getters ui events Bluetooth
17. Parent App E Watch Extension App can’t wake extension
18. Watchkit app made of 2 parts - “App” and extension Extension <-> watch app is a lightweight channel Extension <-> parent app can only be started by the extension Architectural Takeaways
19. A WatchKit App Lifecycle
20. E Watch Extension Initial Launch Watch “App” User launches app Load storyboard init awakeWithContext: Show UI willActivate
21. E Watch Extension Interaction willActivate didDeactivate …various UI-triggered actions…
22. E Watch Extension Interaction willActivate didDeactivate …various UI-triggered actions…
23. E Watch Extension Interaction willActivate didDeactivate …various UI-triggered actions…
24. Stay lightweight in watch extension, especially init and awake UI updates when screen isn’t active are dropped on the floor Lifecycle Takeaways
25. Communication
26. openParentApplication:reply:
27. Polo! Marco?
28. [WKInterfaceController openParentApplication:@{...} reply:^(NSDictionary *replyInfo, NSError *error) { if (error) { NSLog(@"Error from parent: %@", error); } else { //do something with the reply info.... } }]; E Any WKInterfaceController
29. - (void)application:(UIApplication *)application handleWatchKitExtensionRequest:(NSDictionary *)userInfo reply:(void(^)(NSDictionary *replyInfo))reply { reply(@{...}); } AppDelegate
30. openParentApplication:reply: • Will launch your parent app! • Great way to send actions / triggers Pros • Can’t do too many back-to-back (serialized queue) • Launches parent in background mode-only • Have fun with your app lifecycle Cons
31. App Group & NSUserDefaults
32. Parent App E iOS 8 Extension Extension data sharing ex: “com.consumedbycode.slopes.group” App groups x
33. Parent App E iOS 8 Extension Extension data sharing ex: “com.consumedbycode.slopes.group” App groups x
34. Parent App E iOS 8 Extension Extension data sharing ex: “com.consumedbycode.slopes.group” App groups x
35. Anywhere NSUserDefaults *defaults = [NSUserDefaults initWithSuite:@“my.group.name”]; [defaults setInteger:4 forKey@"myKey"]; [defaults synchronize];
36. NSUserDefaults *defaults = [NSUserDefaults initWithSuite:@“my.group.name"]; NSInteger myInt = [defaults integerForKey@"myKey"]; E Anywhere
37. initWithSuite is separate from standardUserDefaults
38. NSUserDefaults • Simple API to serialize and read data Pros • No KVO Cons
39. App Groups & Core Data
40. NSURL *directory = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject]; NSURL *storeURL = [directory URLByAppendingPathComponent:@“myApp.sqlite"]; //init persistent store, etc..
41. Anywhere NSURL *directory = [[NSFileManager defaultManager] containerURLForSecurityApplicationGroupIdentifier:@“ my.group.name”]; NSURL *storeURL = [directory URLByAppendingPathComponent:@“myApp.sqlite"]; //init persistent store, etc.. E
42. Core Data • Reuse existing model • Set up for multi-threading • KVO Pros • Core Data (I kid, I kid) • Bad place to store one-off values to pass around • Need to move DB to App Group container Cons
43. App Groups & Darwin Notification Center
44. pod ‘MMWormhole’
45. Anywhere MMWormhole *wormhole = [[MMWormhole alloc] initWithApplicationGroupIdentifier:@"my.group.name" optionalDirectory:@"wormhole"]; //whenever the data changes… [wormhole passMessageObject:@(5.5) identifier:@"currentSpeed"]; E
46. Anywhere //get the current value NSNumber *currentSpeed = [wormhole messageWithIdentifier:@"currentSpeed"]; //...or subscribe for updates [wormhole listenForMessageWithIdentifier:@"currentSpeed" listener:^(id messageObject) { //do something with the speed }]; E
47. Anywhere [wormhole stopListeningForMessageWithIdentifier:@"currentSpeed"]; E
48. WKInterfaceController - (void)willActivate { [super willActivate]; [self.wormhole listenForMessageWithIdentifier:@"currentSpeed" listener:^(id messageObject) { //do something with the speed, update a label, etc }]; } - (void)didDeactivate { [super didDeactivate]; [self.wormhole stopListeningForMessageWithIdentifier:@"currentSpeed"]; } E
49. MMWormhole • KVO • Great for one-off values Pros • Separate data you have to keep in sync from your model layer Cons
50. openParentApplication:reply: great for actions, bad for lots of data fetching NSUserDefaults: great for data, but no notification of changes CoreData: great for sharing existing model data, bad for one-off messages Darwin Notification Center: consider in place of NSUserDefaults Communication Takeaways
51. Demo time
52. https://developer.apple.com/watchkit/ https://github.com/mutualmobile/MMWormhole http://infinitapps.com/bezel/ Resources