Swift and Objective-C playing together

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Swift & Objective-C Playing together @pepibumur | www.ppinera.es

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SugarRecord Data Storage made easy with Swift (http://github.com/SugarRecord)

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Objective-C without the C Swift !

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Play !

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Play ! Learn !

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Play ! Learn ! Try !

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Swift was Designed to play together

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Bridging

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Objective-C into Swift Project-Bridging-Header.h

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Bridging header // // Use this file to import your target's public headers that you would like to expose to Swift. // // I can import CocoaPods Libraries here! #import // And my Objective-C classes #import "CocaColaAlgorithm.h" Swift implementation // Use here your Objective-C exposed classes let cola = CocaColaAlgorithm.prepareCola()

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Swift into Objective-C Autogenerated ProductName-Swift.h file (Not TargetName!) Swift.swift class NSObjectSwiftClass: NSObject { } ProductName-Swift.h SWIFT_CLASS("_TtC9SwiftObjc18NSObjectSwiftClass") @interface NSObjectSwiftClass : NSObject - (instancetype)init OBJC_DESIGNATED_INITIALIZER; @end

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What's exposed? • Marked with @objc or Objective-C class descendant • public elements • private are exposed if marked with @IBAction, @IBOutlet, or @objc • internal are exposed if the project has an Objective-C bridging header • Objective-C compatible features

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Swift only features • Generics, tuples and Swift enums • Structures defined in Swift • Top-level functions defined in Swift • Global variables defined in Swift • Typealiases defined in Swift • Swift-style variadics • Nested types and curried functions

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No more imports! ! For .swift files in the same target

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Be careful with circular dependencies Don't include Product-Swift.h in your Objc-C .h files

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Use forward declaration @class

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Naming your product Module • Non alpha-numeric characters replaced by "_" (or starting by a number) • XCode generates _ﬁt-Swift.h from the product name 8ﬁt

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What can we do? And what not?

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Inheriting Objective-C classes (Remember to use the @override keyword) class MyCell: UITableViewCell { override init(style: UITableViewCellStyle, reuseIdentifier: String?) { super.init(style: style, reuseIdentifier: reuseIdentifier) } required init(coder aDecoder: NSCoder) { fatalError("init(coder:) has not been implemented") } }

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You cannot subclass Swift classes in Objective-C (Even if the class is a Swift @objc or NSObject class) #if !defined(SWIFT_CLASS) # if defined(__has_attribute) && __has_attribute(objc_subclassing_restricted) # define SWIFT_CLASS(SWIFT_NAME) SWIFT_RUNTIME_NAME(SWIFT_NAME) __attribute__((objc_subclassing_restricted)) SWIFT_CLASS_EXTRA # else # define SWIFT_CLASS(SWIFT_NAME) SWIFT_RUNTIME_NAME(SWIFT_NAME) SWIFT_CLASS_EXTRA # endif #endif SWIFT_CLASS("_TtC9SwiftObjc9ObjcClass") @interface ObjcClass - (instancetype)init OBJC_DESIGNATED_INITIALIZER; @end

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AnyObject is the Swift equivalent of id (But it's a protocol and its type is not know until runtime) if let fifthCharacter = myObject.characterAtIndex?(5) { println("Found \(fifthCharacter) at index 5") } You can use casting if let date = lastRefreshDate as? NSDate { println("\(date.timeIntervalSinceReferenceDate)") }

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Objective-C nils Are implicitly unwrapped in Swift Be careful! The force awakens

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Objective-C - (NSDate *)dueDateForProject:(Project *)project; Swift func dueDateForProject(project: Project!) -> NSDate!

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Extension & Category But swift extension can make classes conform protocols that they didn't extension MyClass: StringLiteralConvertible { typealias ExtendedGraphemeClusterLiteralType = StringLiteralType init(unicodeScalarLiteral value: UnicodeScalarLiteralType) { self.pattern = "\(value)" } init(extendedGraphemeClusterLiteral value: StringLiteralType) { self.pattern = value } init(stringLiteral value: StringLiteralType) { self.pattern = value } }

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Closures & Blocks Fully compatible The only difference is that variables are mutable rather than copied, e.g:

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Objective-C __block CustomObject *myObject = [CustomObject new]; void (^myBlock)() = ^void() { NSLog(@"%@", myObject); }; Swift let customObject: MyObject = MyObject() let myBlock: () -> () = { in println("\(customObject)") }

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FuckingBlockSyntax.com FuckingClosureSyntax.com !

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Comparison Objective-C isEqualTo() - Equality == - Object instance Swift == - Equality === - Object instance

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@objc @objc(ObjcCat) class SwiftCat { @objc(initWithName:) init (name: String) { /*...*/ } } @objc is inferred if it's a NSObject subclass

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Protocols • Swift can adopt Objective-C protocols • Objective-C can adopt Swift protocol if they are NSObjectProtocol Adopting swift protocols in objective-C /** MyProtocol.swift */ @objc protocol MyProtocol: NSObjectProtocol { // Protocol stuff }

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Protocols in Delegate pattern It must be declared as a class type (It can only be conformed by reference types, thus having a weak reference) protocol MyDelegate : class { // methods/properties }

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Cocoa Data Types Some Swift and Objc can be used interchangeably (Remember to import Foundation)

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String turns into NSString let myString: NSString = "123"

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NSLocalizedString Function into NSLocalizedString Macro

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Int, UInt, Float, Double, Bool into NSNumber let n = 42 let m: NSNumber = n

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[AnyObject] into NSArray If casting to NSArray objects have to be AnyObject compatible NSArray into [AnyObject] for myItem in foundationArray as [UIView] { // Do whatever you want }

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NSDictionary into [NSObject: AnyObject] [NSObject: AnyObject] into NSDictionary Keys and values must be instances of a class or bridgeable

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[[MyClass alloc] initWithBird:bird]; MyClass(bird: bird) Failable Initialization: init?(...)

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CocoaPods

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✅ Objective-C pods in Swift ⬜ Swift pods WIP

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With the theory in mind... Moving to Swift advices ✈

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Don't touch your Objc code base! (Unless it requires a refactor. Do it in Swift)

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Most of libraries are in Objc And you can use them in Swift! (be patient and don't try to have everything in Swift)

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Implement Swift on isolated features • Using Swift features internally • With @objc compatible output interface

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Swift libraries... when there is no objc option (or you have a pure Swift project)

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Why?

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But overall

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Resources //MARK: - You should read let swiftTypes = "https://github.com/jbrennan/swift-tips/blob/master/swift_tips.md" let realmAndObjc = "http://realm.io/news/swift-objc-best-friends-forever" let swiftReady = "http://www.toptal.com/swift/swift-is-it-ready-for-prime-time" let swiftImprovesObjc = "http://spin.atomicobject.com/2014/06/13/swift-improves-objective-c/" //MARK: - Slides let slidesURL = "http://bit.ly/1AaKRfv" println("The slides are available here: \(slidesURL)") //MARK: - Contact let emailURL = NSURL(string: "mailto://[email protected]")! UIApplication.sharedApplication().openURL()

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Thanks Doubts?