Swift 2.2 & 3.0 Changes

What to expect from upcoming Swift versions. Presented at Tumblr's CocoaTBH IRL

Transcript

1. CHANGES IN SWIFT 2.2 & 3 COCOATBH IRL, MARCH 2016 JASDEV SINGH
2. SWIFT 2.2 SPRING 2016
3. SWIFT LANGUAGE VERSION BUILD CONFIGURATION #if swift(>=2.2) print("supsup") #else ayy lmao // Not parsed #endif > Only allowed operator is >= > 0.1 is the smallest revision unit.
4. NEW SYNTAX FOR ASSOCIATED TYPES Previously, typealias could be used in two contexts. 1. Type Aliases (alternative name for a type) 2. Associated Types (placeholder for a type in a protocol) Starting in 2.2, the latter will be signaled with the associatedtype keyword (removed in 3.0).
5. associatedtype CONTINUED Moving forward, the following snippet will error out: protocol SomeProtocol { associatedtype Container: SequenceType typealias Element = Container.Generator.Element // X } To get around this, use a protocol extension ⭐ protocol SomeProtocol { associatedtype Container: SequenceType } extension SomeProtocol { typealias Element = Container.Generator.Element }
6. FUNCTION SIGNATURE REFERENCES Overloaded functions can now be referenced with their name and argument labels! struct SomeStruct { func ayy(lmao: String) { } func ayy(lmao: String, sup: String) { } } let func1 = SomeStruct.ayy(_:) let func2 = SomeStruct.ayy(_:sup:)
7. DEBUGGING IDENTIFIER SYNTAX CHANGES __FILE__ -> #file __LINE__ -> #line __COLUMN__ -> #column __FUNCTION__ -> #function __DSO_HANDLE__ -> #dsohandle
8. OBJECTIVE-C SELECTOR GENERATION To avoid the error-prone approach of String literals for selectors, #selector(_) has been introduced: let sel = #selector(UIView.insertSubview(_:atIndex:)) // `sel` is a `Selector` "insertSubview:atIndex:"
9. DEPRECATION OF ++ AND -- "IF WE DIDN'T ALREADY HAVE THESE, WOULD WE ADD THEM TO SWIFT 3?"
10. REMOVAL OF C-STYLE for LOOPS Deprecated in 2.2, removed in 3.0
11. FAILABLE AND THROWING CLASS INITIALIZERS CAN EXIT BEFORE SETTING ALL PROPERTIES Reference types used to require all properties to be set prior to exiting in failable/throwing initializers. This issue has been fixed! !
12. TUPLE COMPARISONS Tuples with Equatable elements are now implicitly Equatable ! (works up to sextuples)
13. @OBJC(...) FOR ENUMERATION CASES Cases within an @objc enumeration can receive special names when being bridged back! @objc enum SomeEnum: Int { @objc(SpecialName) case BridgeCase }
14. PREFER AnyGenerator INITIALIZER OVER anyGenerator anyGenerator will be deprecated in 2.2 and removed in 3.0 (general trend of removing global functions)
15. KEYWORDS AS ARGUMENT LABELS Reserved keywords can now be used as argument labels without backticks (with exception to let, var, and inout)
16. SWIFT 3.0 LATE 2016
17. REMOVAL OF SPECIAL CURRYING SYNTAX // Before func curried(x: Int)(y: String) -> Float { return Float(x) + Float(y)! } // After func curried(x: Int) -> String -> Float { return { (y: String) -> Float in return Float(x) + Float(y)! } }
18. BETTER TRANSLATION OF OBJECTIVE-C APIS INTO SWIFT > SE-0005 > Example Diff
19. REMOVAL OF var PARAMETERS Often confused with inout and only saved a line of code. To get around this use: func ayylmao(n: Int) { var n = n // ... }
20. ABI STABILITY ! "ABI stabilization means that applications [...] compiled with future versions of Swift can interact at a binary level with applications [...] compiled with Swift 3.0."
21. MORE COMPLETE GENERICS > Recursive protocol constraints > Constrained extension protocol conformance > Generic subscripts?
22. API DESIGN GUIDELINES
23. SWIFT TESTING W/ SWIFT PACKAGE MANAGER SE-0019
24. inout TO BECOME A TYPE DECORATOR (x: inout T) -> U
25. FULL LIST OF CHANGES !