Gradual Coordinators

Transcript

1. Gradual Coordinators Alper Cugun-Gscheidel
3. Objective-C
4. –Me "things that are used never stay clean but need to be cleaned perpetually”
5. Gradualism
6. Problem Statement
7. Add Contract Flow
8. Presentation Modes • Navigation controller • Modal presentation (of navigation controller) • Tab presentation (of a navigation controller) • Interstitials • etc.
10. Messy Exits self.dismiss(animated: true, completion: nil) if let mcvc = self.menuContainerViewController { let storyboard = UIStoryboard(name: "Main", bundle: Bundle.main) let vc = storyboard.instantiateViewController(withIdentif ier: "HomeNavigationController") mcvc.centerViewController = vc }
12. –Me again “There are no architectures. Every implementation of an architecture is a collection of patterns, some of which are specific to the architecture and some specific to the application.”
13. Coordinators • “Coordinators Essential tutorial”, Andrey Panov • “An iOS Coordinator Pattern”, Will Townsend • “Coordinators Redux”, Soroush Khanlou • “Improve your iOS Architecture with FlowControllers”, Krzysztof Zabłocki
14. Green Field • Jelly • Apple sauce • Greenfield
15. Does not blend • Protocols • Routers • Factories • Double bookkeeping with children • Cognitive overload
16. Soak
17. Simplification • Inversion of Control • Exit contract • Delegation
18. Code
19. Step by Step 1. Create Delegate Method for each exit point of a View Controller 2. In Coordinator replace initial segue with own presentation in start() 3. In flow replace all calls to performSegue with delegate method call 4. In coordinator implement delegate method to go to the next step (remove/show/push)
20. Delegate Method // CONTRACT @objc protocol SelectSubjectViewControllerDelegate { func selectedCategories(selectedVendors: [[String: AnyObject]], selectedSubjects: [Subject]) } // CONFORMING VIEW CONTROLLER @property (weak, nonatomic) id<SelectSubjectViewControllerDelegate> delegate;
21. start() [self performSegueWithIdentifier:kAddContract sender:self]; // REPLACE WITH UIStoryboard *addContractStoryboard = [UIStoryboard storyboardWithName:@"AddContract" bundle:nil]; SelectSubjectViewController *ssvc = (SelectSubjectViewController *)[addContractStoryboard instantiateViewControllerWithIdentifier:@"SelectSubje ctViewController"]; ssvc.delegate = self; [self.navigationController pushViewController:ssvc animated:YES];
22. performSegue swap // REPLACE [self performSegueWithIdentifier:kSegue sender:self]; // AND if ([segue.identifier isEqualToString:kSegue]) {} // WITH [self.delegate selectedCategoriesWithSelectedVendors:self.sele ctedVendors selectedSubjects:self.selectedSubjects];
23. implement delegate extension VoldersTabBarController: SelectSubjectViewControllerDelegate { func selectedCategories(selectedVendors: [[String : AnyObject]], selectedSubjects: [Subject]) { let storyboard = UIStoryboard(name: "AddContract", bundle: nil) let vc = storyboard.instantiateViewController(withIdentifier: "SelectVendorViewController") if let selectVendorVC = vc as? SelectVendorViewController { selectVendorVC.selectedVendors = NSMutableArray(array: selectedVendors) selectVendorVC.subjects = selectedSubjects selectVendorVC.delegate = self } if let nvc = self.viewControllers?[2] as? UINavigationController { nvc.pushViewController(vc, animated: true) } } }
24. Issues • Loss of locality (lots of code in different places) • Xcode does not like empty segues • Dual class UITabbarController subclass to be ad-hoc Coordinator • Not neatly composable • Navigation actions are a (fixable/irrelevant) issue
25. How to architect • Read everything • Be realistic • Soak • Take it step-by-step
26. Thanks! @alper (twitter/insta/github)