え!? Swift使ってるのにそんな書きかたしてるのですか!?

iOSアプリをSwiftらしいコードで記述するために

Transcript

1. ͑!? Swift࢖ͬͯΔͷʹͦΜͳ
   ॻ͖͔ͨͯ͠ΔͷͰ͔͢!?
   potatotips#11
   @yuseinishiyama
   

   View Slide

2. Who am I?
   • Mobile app engineer at Cookpad Inc.
   • Develop apps for iOS
   • Regulate “Auto Layout” day after day… :’-(
   • I’m interested in
   • Metal (new graphics API of Apple)
   • Functional programming (with Swift)
   • Reactive programming (Reactive Cocoa)
   

   View Slide

3. In Objective-C era…
   @interface SomeClass : NSObject
   @property (nonatomic, strong) NSString *someString;
   @end
   !
   @implementation SomeClass
   !
   - (void)setSomeString:(NSString *)someString
   {
   _someString = someString;
   [self doSomething];
   }
   !
   - (void)doSomething
   {
   NSLog(@"I don't feel like doing anything...");
   }
   !
   @end
   ؆୯ʹ୅ೖ࣌ʹॲཧΛߦ͏͜ͱ͕Ͱ͖ͨ
   

   View Slide

4. With Swift
   class SomeClass {
   private var backingStore = ""
   var value: String {
   get {
   return backingStore
   }
   set {
   backingStore = newValue
   doSomething()
   }
   }
   func doSomething() {
   println("I don't feel like doing anything.")
   }
   }
   85'
   

   View Slide

5. Keep calm
   class SomeClass {
   var someString: String = "" {
   didSet {
   doSomething()
   }
   }
   func doSomething() {
   println("Now I’m sleeping. Please don’t disturb.")
   }
   }
   XJMM4FU΍EJE4FUΛ࢖͑͹ಉ͜͡ͱ͕࣮ݱՄೳ
   

   View Slide

6. Coalesce fallback
   class Person {
   var name: String!
   }
   !
   var quietPerson = Person()
   quietPerson.name = "Tom"
   !
   var hisName: String!
   !
   if quietPerson.name != nil {
   hisName = quietPerson.name
   }
   else {
   hisName = "I can't recognize what he says"
   }
   

   View Slide

7. Use `??`
   class Person {
   var name: String!
   }
   !
   var quietPerson = Person()
   quietPerson.name = "Tom"
   !
   var hisName = quietPerson.name ?? "I can't recognize what he says"
   

   View Slide

8. (Annoying) weakSelf pattern
   class SomeClass {
   var ivar: Int?
   func methodA(function: ()->()) {
   function()
   }
   func methodB() {
   weak var weakSelf = self
   methodA { () -> () in
   weakSelf!.ivar = 3
   }
   }
   }
   

   View Slide

9. use `[unowned self]`
   class SomeClass {
   var ivar: Int?
   func methodA(function: ()->()) {
   function()
   }
   func methodB() {
   methodA { [unowned self] () -> () in
   self.ivar = 3
   }
   }
   }
   

   View Slide

10. Static variables in function
    - (BOOL)toggleSwitch
    {
    static BOOL aSwitch = true;
    aSwitch = !aSwitch;
    return aSwitch;
    }
    

    View Slide

11. 4XJGU͸ߏ଄ମͰ͔͠TUBUJDม਺Λαϙʔ
    τ͍ͯ͠ͳ͍ʜ
    

    View Slide

12. Use struct
    func toggleSwitch() -> Bool {
    struct Switch {
    static var aSwitch = true
    }
    Switch.aSwitch = !Switch.aSwitch
    return Switch.aSwitch
    }
    

    View Slide

13. Cast
    var anyObject: AnyObject? = "WE ARE UPPERCASE"
    if anyObject is String {
    let string = anyObject as String
    println(string.lowercaseString + "?")
    }
    ৑௕ʁ
    

    View Slide

14. You can check, cast and bind
    in one line
    !
    if let string = anyObject as? String {
    println(string.lowercaseString + "?")
    }
    

    View Slide

15. Trailing closure
    func methodX(i: Int, function: ()->(String)) {
    function()
    }
    !
    methodX(1, { () -> (String) in return "Do nothing" } )
    !
    methodX(1) { () -> (String) in return "Do nothing" }
    

    View Slide

16. Swift array supports
    map, filter and reduce
    class Vehicle {
    var numberOfTires: Int = 0
    }
    class Car: Vehicle {
    override init() {
    super.init()
    numberOfTires = 4
    }
    }
    class Bicycle: Vehicle {
    override init() {
    super.init()
    numberOfTires = 2
    }
    }
    class Unicycle: Vehicle {
    override init() {
    super.init()
    numberOfTires = 1
    }
    }
    let vehicles = [Car(), Car(), Unicycle(), Bicycle(), Car(), Unicycle()]
    var numberOfAllTires = vehicles.map{ $0.numberOfTires }.reduce(0, +)
    

    View Slide

17. Nested function
    func setUpViews() {
    func setupBarButton() {
    // set up bar buttons
    }
    func setupRefreshControl() {
    // set up refresh control
    }
    setupBarButton()
    setupRefreshControl()
    }
    είʔϓΛอͬͨ··ɺॲཧΛߏ଄Խ͢Δ͜ͱ͕Ͱ͖Δ
    

    View Slide

18. Enum with method
    enum MyTableViewSection: Int {
    case A = 0, B, C, D
    func heightForCell() -> CGFloat {
    switch self {
    case A:
    return 30
    case B:
    return 44
    case C:
    return 80
    case D:
    return 44
    }
    }
    }
    !
    func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) ->
    CGFloat {
    return MyTableViewSection(rawValue: indexPath.section)!.heightForCell()
    }
    ؔ࿈͢ΔॲཧΛ&OVNଆʹҠৡͨ͠΄͏͕Մಡੑ͕ߴ͍
    

    View Slide

19. Any Questions?
    

    View Slide