Advanced Flow Controllers

Transcript

1. Flow Controllers
2. Advanced Flow Controllers
3. Shoutouts • Olivier Collet (http://ocollet.com/flow-controller/) • Sebastien Morel (Talk to him about it)
4. Massive View Controllers
5. Massive View Controllers • View setup and layout • Core Data fetching • Network Calls • Delegate of everything • Accessing global state • Navigation logic • Animation logic
6. I could go on...
7. What is your ideal UIViewController?
8. To me, it looks like this: • Everything that goes into the controller is clearly defined • All the actions the controller can make are clearly defined • It's oblivious to the outside world • It doesn't access any application state through singletons
9. To string these VCs together, we need a puppet master
10. In other words, a flow controller!
11. Example @protocol FavoritesTableViewDelegate - (void)callContact:(Contact *)contact; - (void)navigateToContactInfo:(Contact *)contact; @end @interface FavoritesTableView : UIViewController @property id<FavoritesTableViewDelegate> flowController - (instancetype)initWithContacts:(NSArray *)favorites; @end
12. What's a flow controller? • Plain old NSObject • Sets up and orchestrates transitions between multiple view controllers • Handles a logical portion of the application flow • Contains relevant state for that portion of the app
13. @interface FavoritesFlowController : NSObject <FavoritesTableViewDelegate> @property UINavigationController *navController @end @implementation - (void)callContact:(Contact *)contact { CallController *ctrl = [CallController alloc] initWithFlowController:self]; [self.navController presentViewController:ctrl animated:YES]; } - (void)navigateToContactInfo:(Contact *)contact { ContactInfoController *ctrl = [ContactInfoController alloc] initWithFlow:self]; [self.navController pushViewController:ctrl animated:YES]; } @end
14. Tips and Tricks
15. Avoiding Singletons • Flow controllers are a logical place to hold bits of application state • View controllers can be injected with the necessary state, avoiding singletons!
16. Inheritance chaining - 'Explore' mode @interface LoginEnabledFlowController : NSObject - (void)showLoginIfNecessaryWithCompletion:(void (^)(User *user, BOOL success)); @end
17. Inheritance chaining - Repeating view controllers @interface TimelineEnabledFlowController : NSObject <TweetCellDelegate> @end @interface TimelineFlowController : TimelineEnabledFlowController @end @interface MeFlowController : TimelineEnabledFlowController @end
18. Application events Implement UIApplicationDelegate in your flow controllers to forward UIApplication events
19. But wait, there's more!
20. Unit test your View Controllers! • You know what needs to go in and come out • Mocking dependencies is easy
21. Interested in a sample app? If there's enough interest I'll throw something up on Github
22. Thanks! @frankacy