Potatotips 15/4/2015

1. 10 things you should
know about WatchKit
before you submit
trippiece Inc.
@kitasuke

2. 1. How to
communicate and
share data

3. openParentApplication:reply:
InterfaceController.m
[WKInterfaceController openParentApplication:@{@"action": @"count"} reply:^(NSDictionary *replyInfo, NSError *error)] {
if (error) {
// error
} else {
// do something
}
}];
application:handleWatchKitExtensionRequest:reply:
AppDelegate.m
- (void)application:(UIApplication *)application handleWatchKitExtensionRequest:(NSDictionary *)userInfo reply:(void(^)(NSDictionary *replyInfo))reply {
// do something
}

4. Pros
- Can let your containing iOS app execute some tasks in the
background
- Doesn't matter whether your containing iOS app is currently
running or not
Cons
- If you call multiple times in quick succession, each
subsequent call is delayed
- Should always be triggered by your WatchKit app

5. Darwin Notification Center
MMWormhole

6. self.wormhole = [[MMWormhole alloc] initWithApplicationGroupIdentifier:@"group.com.mutualmobile.wormhole"
optionalDirectory:@"wormhole"];
[self.wormhole passMessageObject:@{@"buttonNumber" : @(1)} identifier:@"button"];
[self.wormhole listenForMessageWithIdentifier:@"button" listener:^(id messageObject) {
self.numberLabel.text = [messageObject[@"buttonNumber"] stringValue];
}];

7. Pros
- Simple and fast
- Can be used for other extensions, not only WatchKit
Cons
- WatchKit app should be awake to receive immediately
- Keep sending message to WatchKit app to always show the
right data

8. 2. Background task

9. Make sure that you handle the reply in
background task
AppDelegate.m
- (void)application:(UIApplication *)application handleWatchKitExtensionRequest:(NSDictionary *)userInfo reply:(void (^)(NSDictionary *))reply {
__block UIBackgroundTaskIdentifier watchKitHandler;
watchKitHandler = [[UIApplication sharedApplication] beginBackgroundTaskWithName:@"backgroundTask" expirationHandler:^{
watchKitHandler = UIBackgroundTaskInvalid;
}];
reply(nil)
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)NSEC_PER_SEC * 1), dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0),^{
[[UIApplication sharedApplication] endBackgroundTask: watchKitHandler];
});
}

10. 3. Handoff

11. Use handoff to open your
containing iOS app to ask user to
allow any kinds of permission
required for WatchKit
WatchKit app → Containing iOS app

12. 4. Current location on
map

13. Use custom image for annotation
Map can display no more than five annotations at a time

14. 5. Group

15. Use group to handle your UI

16. 6. Notifications

17. 3 steps
1. Got sound and vibration
2. Look at your Apple Watch
3. Keep looking (Optional)

18. 7. Bundle name
VS
Bundle display name

19. Containing iOS app's Bundle name is for app name in
companion app
WatchKit Extension's Bundle display name is for sash
name
It's weird, so might be changed in the future...

20. 8. App icons for
image assets

21. Do not set same asset name for
containing iOS app and WatchKit
app

22. 9. Xcode 6.2
VS
Xcode 6.3

23. A huge difference
Xcode 6.2 Xcode 6.3

24. 10. Realm

25. WatchKit & Realm
Best combination ever!
What's Realm?
Tutorial: Sharing Data between WatchKit & your App, with Realm

26. Any questions?