Migrating Objective-C to Swift

Sharing thoughts about migrating from Objective-C to Swift.
Why, How and What. This presentation was held on Munich iOS Meetup 2015/12/02. http://www.meetup.com/de/The-Munich-iOS-Developers-Meetup/events/226586543/

Transcript

1. func migrating(from: ObjC) -> Swift! [objC autorelease]
2. Why?
3. https://twitter.com/clattner_llvm
4. WWDC Appearances swift objective-c 2014 19 63 2015 71 15
5. „…in future, all the 
 nice things will only 
 come to swift…“ Apple Software Engineer
6. What will you lose on the way?
7. * [ ] .h .m Good old Friends
8. Runtime Dynamics NSInvocation NSMethodSignature [obj load] nil messaging Macros https://developer.apple.com/swift/blog/?id=19
9. What will you gain?
10. Types Autoclosures Structs Generics Implicit Member Expressions Custom Operators Typealiases Enums Currying Recursive Enumerations Property Observers Protocol Extensions Generators Subscripts Optionals Lazyness Pattern Matching Tuples Immutability ErrorType Access Control
11. Simplicity view.backgroundColor = .redColor() [view setBackgroundColor: [UIColor redColor]]
12. @warn_unused_result func flatMap<T> (@noescape _ transform: 
 (Self.Generator.Element) throws -> T?) 
 rethrows -> [T] Kinda Simplicity https://developer.apple.com/library/ios/documentation/Swift/Reference/ Swift_SequenceType_Protocol/index.html
13. https://github.com/typelift/Swiftz/blob/master/Swiftz/EitherExt.swift Not-So-Simplicity-At-All
14. What will remain?
15. SDK XYZKit Model View Controller Retain Cycles Xcode
16. How to start?
17. Existing Objective-C Project No Warnings https://developer.apple.com/library/ios/documentation/Swift/Conceptual/ BuildingCocoaApps/index.html#//apple_ref/doc/uid/TP40014216-CH2-ID0 Using Swift with Cocoa and Objective-C
18. Bridging Header Add Imports as you need them Automatically generated by compiler Generated Header …using obj-c in swift… …using swift in obj-c…
19. Optimize Obj-C for Swift NS_ASSUME_NONNULL_BEGIN nonnull|nullable|null_unspecified NSArray<__kindof UIView *> *someViews; https://developer.apple.com/videos/play/wwdc2015-401/
20. Try to avoid designing Swift for Obj-C You’ll have access to anything within a class or protocol that’s 
 marked with the @objc attribute as long as it’s compatible with Objective-C. 
 This excludes Swift-only features such as those listed here: Generics Tuples Enumerations defined in Swift without Int raw value type Structures defined in Swift Top-level functions defined in Swift Global variables defined in Swift Typealiases defined in Swift Swift-style variadics Nested types Curried functions https://developer.apple.com/library/ios/documentation/Swift/ Conceptual/BuildingCocoaApps/MixandMatch.html#//apple_ref/doc/ uid/TP40014216-CH10-ID122
21. Adding 
 New 
 Controller Refactor Existing Controller 1 2 Where to use Swift 
 in the beginning? It`s ok to build a parallel universe
22. Find New Solutions™ and yeah, use guard…
23. Swift will make your life easier title = ~"Select Title" Custom Operator for i18n
24. struct Storyboard { struct Segues { static let channelInfo = "channelInfo" } struct Cells { static let channelCell = "channelCell" } struct ReuseView { static let sectionHeader = "header" } } Swift will make your life easier Define Segues, Identifier, and so forth
25. Swift will make your life easier @IBOutlet weak var myCellView: UIView! { didSet { myCellView.backgroundColor = .redColor() myCellView.layer.masksToBounds = true myCellView.layer.cornerRadius = 2 } } Configure Views after outlet binding
26. override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) { switch (segue.identifier, segue.destinationViewController, collectionView?.indexPathsForSelectedItems()?.first) { case let(Storyboard.Segues.info?, controller as InfoController, index?): controller.channel = channels?.get(index.row) default: break } } Swift will make your life easier Pattern Match Your Life
27. Swift will make your life easier for (a, b) in (0...2).zipWithFollower() { print(a, b) // 0,1 1,2 2,nil } public struct ZipWithFollower<T: SequenceType>: SequenceType { public typealias Generator = AnyGenerator<(T.Generator.Element, T.Generator.Element?)> let sequence: T public init(_ sequence: T) { self.sequence = sequence } public func generate() -> Generator { var generator1 = sequence.generate() var generator2 = sequence.generate() _ = generator2.next() return anyGenerator { guard let element1 = generator1.next() else { return nil } return (element1, generator2.next()) } } } Clean up your control flow
28. struct StateFlow<S,T> { let at: S let to: T -> S } let wizardFlow: [StateFlow<WizardState, WizardConfig>] = [ from(.Init).to { config in if config.useCustomSeletion { return .ComponentWizard } return .ComponentSelection } ] Swift will make your life easier Double Down on Types
29. @elmkretzer Go Swift! www.symentis.com