Swift, Meet Storyboard

Swift London (October 19, 2015) talk. Talk about Natalie - Storyboard Code Generator presenting my approach to the "problem" of Storyboards and Swift.

Transcript

1. Swift London, 19 Oct 2015 Swift, meet Storyboard
2. Welcome Marcin Krzyżanowski blog.krzyzanowskim.com @krzyzanowskim
3. Storyboards “A storyboard is a visual representation of the user interface of an iOS application, showing screens of content and the connections between those screens”
4. Storyboard » scenes » segues between scenes » controls used to trigger the segues
5. Storyboard » graphical representation of a interface » visual editor: Interface Builder » not a code » structured XML document (compiled to nibs) » loaded in runtime
8. Storyboard, meet Swift
9. As it is » string based identifiers » UIViewController
10. Problems » error prone refactoring » traversing view controllers/storyboards » massive Storyboard (not necessarily) » more
11. Strings everywhere
12. Strings everywhere let storyboard = UIStoryboard(name: "Main", bundle: nil) let vc = storyboard.instantiateViewControllerWithIdentifier("MainViewController")
13. Strings everywhere - refactoring week later storyboard.instantiateViewControllerWithIdentifier("ZweiMainViewController") *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Storyboard (<UIStoryboard: 0x7fea2871ccf0>) doesn't contain a view controller with identifier 'ZweiMainViewController'' *** First throw call stack: ( 0 CoreFoundation 0x0000000104f88f65 __exceptionPreprocess + 165 1 libobjc.A.dylib 0x0000000106c1adeb objc_exception_throw + 48 2 UIKit 0x0000000105e855d4 -[UIStoryboard instantiateInitialViewController] + 0 )
14. Strings everywhere - Refactoring func performSegueWithIdentifier(identifier: String, sender: AnyObject?) *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Receiver (<NatalieExample.MainViewController: 0x7f93e2761eb0>) has no segue with identifier 'GoToMainView'' *** First throw call stack: ( 0 CoreFoundation 0x000000010634df65 __exceptionPreprocess + 165 1 libobjc.A.dylib 0x0000000107fdfdeb objc_exception_throw + 48 )
15. UIViewController everywhere func instantiateInitialViewController() -> UIViewController? func instantiateViewControllerWithIdentifier(identifier: String) -> UIViewController returning type? I don't know.
16. as! instantiateInitialViewController() as! OtherViewController Could not cast value of type 'MainViewController' to 'OtherViewController'.
17. Swift, meet Storyboard
19. compile time safety Strong Type System
20. Wouldn't be nice go from this: storyboard.instantiateViewControllerWithIdentifier("MainViewController") to this storyboard.instantiateViewController(MainViewController) and feel safe
21. Parse and conquer Layer - .storyboard Layer - source code
22. Parse and conquer Layer - .storyboard Layer - generator Layer - source code
23. Storyboard, Swift, meet Natalie
25. Natalie Storyboard Code Generator
26. Natalie » Open Source (github: krzyzanowskim/Natalie) » CLI tool » Swift script » #!/usr/bin/env xcrun -sdk macosx swift » Homebrew » $ brew install natalie
27. Storyboards.swift
28. Natalie Integrates with Xcode Build Phases
29. View Controllers struct Storyboards { struct Main { static func instantiateViewController<T: UIViewController>(type: T.Type) -> T? static func instantiateMainViewController() -> MainViewController static func instantiateSecondViewController() -> ScreenTwoViewController } struct Settings { ... } } Instantiate view controllers: let vc = Storyboards.Main.instantiateViewConrtoller(MainViewConrtoller) let vc = Storyboards.Main.instantiateMainViewController() let vc = Storyboards.Main.instantiateSecondViewController() Notice: "vc" has right type:
30. Segues extension MainViewController { enum Segue: String, CustomStringConvertible, SegueProtocol { case ScreenOneSegueButton = "Screen One Segue Button" var kind: SegueKind? // .Push, .Modal, etc... var identifier: String? var destination: UIViewController.Type? } }
31. Segues var destination: UIViewController.Type? { switch (self) { case ScreenOneSegueButton: return ScreenOneViewController.self case ScreenOneSegue: return ScreenOneViewController.self } } in theory: MainViewController.Segue.ScreenOneSegue.destination!.init(nibName: nil, bundle: nil)
32. Perform Segues vc.performSegue(MainViewController.Segue.ScreenOneSegue) override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) { if segue == MainViewController.Segue.ScreenOneSegue { // handle segue } }
33. More » UITableView reusable cells » UICollectionView reusable cells » Compare segues (segue1 == segue2)
34. Recap » Storyboard is external to the code » Strings are error prone » Swift is Strongly Typed » Middleman generator can create bridge between two worlds » Natalie
36. Thank you Marcin Krzyżanowski blog.krzyzanowskim.com @krzyzanowskim