Effective Migration to Mac Catalyst

Starting in macOS Catalina, it’s possible to compile UIKit apps to run on macOS. This new environment can be confusing, since parts of UIKit work differently, and parts of AppKit are available to your iPad app! We’ll explore how to adapt your iPad app for Mac effectively and take a closer look into implementing macOS features like menu bars, tool bars, and window controls with UIKit.

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1. Effective Migration to Mac Catalyst Noah Gilmore @noahsark769 Swift India, July 26th 2019
2. @noahsark769 What is Catalyst? - Introduced at WWDC 2019 - Allows a UIKit codebase to compile into an AppKit Mac app
3. @noahsark769 What is Catalyst? UIKit UIView, UIWindow, UIViewController, ... AppKit NSView, NSWindow, NSViewController, ...
4. @noahsark769 What is Catalyst? Catalyst UIKit UIView, UIWindow, UIViewController, ... AppKit NSView, NSWindow, NSViewController, ...
5. @noahsark769 What is Catalyst? - “Mac Catalyst”, “UIKitForMac”, “iPad Apps for Mac” (formerly “Marzipan”) refer to the same thing
6. @noahsark769 PlanGrid
7. @noahsark769 CIFilter.io
8. @noahsark769 https://github.com/noahsark769/CatalystPlayground
9. @noahsark769 Agenda - Beyond the checkbox - Mac patterns in UIKit - AppKit bundles (and demo) - Should I use Catalyst?
10. Beyond the Checkbox
11. @noahsark769 Check the checkbox
12. @noahsark769 Things that might not work - UIWebView - CoreTelephony (used by analytics libraries) - Your cross-platform static library (.a) - Things that don’t make sense: ARKit, etc @noahsark769
13. @noahsark769 Conditional compilation #if targetEnvironment(macCatalyst) import AppKit #endif
14. @noahsark769 Conditional compilation This will cause a link error! #if canImport(UIKit) print(UIWebView.self) #endif
15. @noahsark769 Conditional compilation WARNING: The second statement will be printed! #if os(macOS) print("Mac") #else print("iOS") #endif
16. @noahsark769 Dependencies - Submit pull requests or support tickets for dependencies - Request distribution of static libraries in .xcframework format
17. Mac Patterns in UIKit
18. @noahsark769 CatalystPlayground - Demonstrates all of these patterns - https://github.com/noahsark769/CatalystPlayground
19. @noahsark769 AppKit #if targetEnvironment(macCatalyst) import AppKit #endif
20. @noahsark769 Windows
21. @noahsark769 Windows - Use UISceneSession APIs in the same way as on iOS
22. @noahsark769 Windows UIApplication.shared.requestSceneSessionActivation( nil, userActivity: nil, options: nil, errorHandler: nil )
23. @noahsark769 Windows guard let containingScene = self.view.window?.windowScene else { return } UIApplication.shared.requestSceneSessionDestruction( containingScene.session, options: nil, errorHandler: nil )
24. @noahsark769 Windows - New windows assume system-assigned size and position - When the user drags, windows resize and update your autolayout constraints - No way to update the size or position of the window with code
25. @noahsark769 App Menus
26. @noahsark769 App Menus - Use UIMenuBuilder (on your app delegate)
27. @noahsark769 App Menus override func buildMenu(with builder: UIMenuBuilder) { super.buildMenu(with: builder) builder.insertChild(UIMenu( __title: "Jump", image: nil, identifier: UIMenu.Identifier(rawValue: "jump"), options: [], children: [ // ... ] ), atEndOfMenu: .view) }
28. @noahsark769 App Menus - Use a child UIKeyCommand for keyboard shortcut enabled items - Can also be used for non-menu keyCommands on your first responder let command = UIKeyCommand( input: "J", modifierFlags: [.command], action: #selector(self.jumpSelected(_:)) ) command.title = "Jump to Windows"
29. @noahsark769 App Menus - Use UICommand for items without shortcuts let noShortcutCommand = UICommand( __title: "No shortcut", image: nil, action: #selector(self.noShortcutSelected), propertyList: nil )
30. @noahsark769 App Menus - Catalyst automatically provides a menu based on the app’s configuration
31. @noahsark769 Touch Bar extension TouchBarViewController: NSTouchBarProvider { var touchBar: NSTouchBar? { let bar = NSTouchBar() let identifier = NSTouchBarItem.Identifier(rawValue: "clickme") bar.defaultItemIdentifiers = [identifier] bar.templateItems = [ NSButtonTouchBarItem( identifier: identifier, title: "button", target: self, action: #selector(didTapClickMe(_:)) ) ] return bar } }
32. @noahsark769 Touch Bar - All system default touch bar items available (color picker, slider, etc) - No NSCustomTouchBarItem
33. @noahsark769 Tool Bar
34. @noahsark769 Tool Bar - UIWindowScene has a UITitleBar which you can give an NSToolbar - Initialize an NSToolbarItem with a UIBarButtonItem - Custom views (and images) are not supported - Import <UIKit/NSToolbar+UIKitAdditions.h>
35. @noahsark769 Tool Bar #if targetEnvironment(macCatalyst) if let titlebar = scene.titlebar { let toolbar = NSToolbar(identifier: "toolbar") toolbar.delegate = self titlebar.toolbar = toolbar titlebar.titleVisibility = .hidden } #endif
36. extension SceneDelegate: NSToolbarDelegate { var identifiers: [NSToolbarItem.Identifier] { return [ NSToolbarItem.Identifier(rawValue: "test"), .flexibleSpace, NSToolbarItem.Identifier(rawValue: "other") ] } func toolbarDefaultItemIdentifiers(_ toolbar: NSToolbar) -> [NSToolbarItem.Identifier] { return self.identifiers } func toolbarAllowedItemIdentifiers(_ toolbar: NSToolbar) -> [NSToolbarItem.Identifier] { return self.identifiers } // ... }
37. @noahsark769 Tool Bar func toolbar( _ toolbar: NSToolbar, itemForItemIdentifier itemIdentifier: NSToolbarItem.Identifier, willBeInsertedIntoToolbar flag: Bool ) -> NSToolbarItem? { switch itemIdentifier.rawValue { case "test": let item = NSToolbarItem( itemIdentifier: itemIdentifier, barButtonItem: UIBarButtonItem( barButtonSystemItem: .add, target: self, action: #selector(didTapAddButton) ) ) return item default: return nil } }
38. @noahsark769 Other AppKit components - Drag and Drop - UIDragInteraction, UIDropInteraction, beta 4 issues - Context Menus - UIContextMenuInteraction - File access - UIDocumentPickerViewController
39. @noahsark769 How much of AppKit can I import? - Pretty much just NSTouchBar and NSToolbar - No direct access to NSWindow - No complicated views like NSTableView
40. AppKit Bundles
41. @noahsark769 AppKit Bundles - Write an AppKit Plug-In bundle and import using NSBundle - Plug-In bundles have access to the full AppKit runtime (NSApplication, NSWindow, etc) - Present panels, control windows, etc - Communicate with UIKit via NotificationCenter or Obj-C interface - No mixing UIKit and AppKit view hierarchies
42. @noahsark769 Demo time https://github.com/noahsark769/SwiftIndiaDemo
43. Should I use Catalyst?
44. New macOS app without iPad equivalent Consider using SwiftUI or AppKit instead ❌ @noahsark769
45. New, cross-platform app Consider using SwiftUI with shared Views ❌ @noahsark769
46. Don’t want to learn AppKit, like me AppKit is more approachable than ever ❌ @noahsark769
47. ✅ Significant existing UIKit iPad app ✅ Small number of external dependencies ✅ Little need for macOS-specific UI ✅ Experimental feature support @noahsark769
48. Further reading - WWDC 2019 #205: Introducing iPad Apps for Mac - WWDC 2019 #235: Taking iPad Apps for Mac to the Next Level - WWDC 2019 #212: Introducing Multiple Windows on iPad - Ultimate Catalyst Guide - Beyond the Checkbox with Catalyst and AppKit @noahsark769
49. Thank you