Swift, meet Objective-C

Transcript

1. ! Swift, meet Objective-C !
   Twitter: @DanToml
   Email: Dan@Tomlinson.io
   

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2. !
   

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3. In the sharp, square
   bracketed embrace of
   Objective-C
   — @AndrewJClark
   

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4. All objective-c written now is technical debt
   

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5. ...but so is all of your
   Swift.
   

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6. You can use them together
   

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7. A whole bunch of new developers are going to be
   Swift only.
   

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8. Starting out
   

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9. Starting out
   Bridging Header
   //
   // Use this file to import your target's public headers that you would like to expose to Swift.
   //
   #import "Person.h"
   #import "PersonController.h"
   #import "CoreDataController.h"
   

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10. Objective-C -> Swift
    

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11. The bridging header
    // ReactiveCocoa-Bridging-Header.h
    //
    // Use this file to import your target's public headers that you would like to expose to Swift.
    //
    #import "RACCommand.h"
    #import "RACDisposable.h"
    #import "RACEvent.h"
    #import "RACScheduler.h"
    #import "RACTargetQueueScheduler.h"
    #import "RACSignal.h"
    #import "RACSignal+Operations.h"
    #import "RACStream.h"
    #import "RACSubscriber.h"
    

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12. Method Names
    // Objective-C
    - (instancetype)initWithArray:(NSArray *)array title:(NSString *)title;
    // Swift
    init!(array: [AnyObject]!, title: String!)
    

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13. Method Names
    // Objective-C
    - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions;
    // Swift
    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool
    

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14. Nullability
    • __nullable
    • __nonnull
    • __null_resettable // Properties only.
    • null_unspecified // Default.
    

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15. Nullability
    Before
    // Objective-C
    @interface XYZList : NSObject
    - (XYZListItem *)itemWithName:(NSString *)name;
    @property (copy, readonly) NSArray *allItems;
    @end
    // Swift
    class XYZList : NSObject, NSCoding, NSCopying {
    func itemWithName(name: String!) -> XYZListItem!
    @NSCopying var allItems: [AnyObject]! { get }
    }
    

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16. Nullability
    After
    // Objective-C
    @interface XYZList : NSObject
    - (XYZListItem * __nullable)itemWithName:(NSString * __nonnull)name;
    @property (copy, readonly) NSArray * __nonnull allItems;
    @end
    // Swift
    class XYZList : NSObject, NSCoding, NSCopying {
    func itemWithName(name: String) -> AAPLListItem?
    @NSCopying var allItems: [AnyObject] { get }
    }
    

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17. Swift -> Objective-C
    

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18. What can be bridged?
    • Classes
    

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19. Classes
    // Swift
    @objc class MySwiftNSObject {
    var array: [String]
    init(array: [String]) {
    self.array = array;
    }
    }
    // Objective-C
    @interface MySwiftNSObject
    @property (nonatomic, copy) NSArray * __nonnull array;
    - (instancetype)initWithArray:(NSArray * __nonnull)array OBJC_DESIGNATED_INITIALIZER;
    @end
    

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20. What can be bridged?
    • Classes
    • Protocols
    

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21. Protocols
    @objc protocol Edible {
    func eat()
    }
    @protocol Edible {
    - (void)eat;
    }
    

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22. What can be bridged?
    • Classes
    • Protocols
    • Methods
    

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23. Methods
    func genericFunction(param: T) // Not bridged
    func defaultParameterFunction(param: String = "Hi") // Not bridged
    func function(param: String)
    - (void)function:(NSString * __nonnull)param;
    

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24. What can be bridged?
    • Classes
    • Protocols
    • Methods
    • Properties
    

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25. Properties
    // Swift
    let forname: String
    var surname: String
    // Objective-C
    @property (nonatomic, readonly, copy) NSString * __nonnull forname;
    @property (nonatomic, copy) NSString * __nonnull surname;
    

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26. Properties
    KVO (Key Value Observing)
    dynamic var name: String
    object.addObserver(self,
    forKeyPath: "name",
    options: .New,
    context: &myContext)
    

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27. What can be bridged?
    • Classes
    • Protocols
    • Methods
    • Properties
    • Enums
    

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28. Enums
    @objc enum MyEnum : Int {
    case SomeValue = 0
    case AnotherValue = 1
    }
    typedef NS_ENUM(NSInteger, MyEnum) {
    MyEnumSomeValue = 0,
    MyEnumAnotherValue = 1
    };
    

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29. Bridging limitations !!!
    No:
    - Structs
    - Functions
    - Operators
    - Generics
    - Subclassing Swift classes in objective-c
    

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30. Roundup
    

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31. Further Resources
    Apple
    • WWDC Session 406 (Integrating Swift with Objective-C)
    • WWDC Session 407 (Swift Interoperability in Depth)
    Blog Posts
    • https://mikeash.com/pyblog/friday-qa-2014-08-15-swift-
    name-mangling.html
    

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32. Questions?
    Twitter: @DanToml
    Email: Dan@Tomlinson.io
    

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