え!? Swift使ってるのにそんな書きかたしてるのですか!?

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

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)

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

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'

5. Keep calm class SomeClass { var someString: String = ""

   { didSet { doSomething() } } func doSomething() { println("Now I’m sleeping. Please don’t disturb.") } } XJMM4FU΍EJE4FUΛ࢖͑͹ಉ͜͡ͱ͕࣮ݱՄೳ

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" }

7. Use `??` class Person { var name: String! } !

   var quietPerson = Person() quietPerson.name = "Tom" ! var hisName = quietPerson.name ?? "I can't recognize what he says"

8. (Annoying) weakSelf pattern class SomeClass { var ivar: Int? func

   methodA(function: ()->()) { function() } func methodB() { weak var weakSelf = self methodA { () -> () in weakSelf!.ivar = 3 } } }

9. use `[unowned self]` class SomeClass { var ivar: Int? func

   methodA(function: ()->()) { function() } func methodB() { methodA { [unowned self] () -> () in self.ivar = 3 } } }

10. Static variables in function - (BOOL)toggleSwitch { static BOOL aSwitch

    = true; aSwitch = !aSwitch; return aSwitch; }

11. 4XJGU͸ߏ଄ମͰ͔͠TUBUJDม਺Λαϙʔ τ͍ͯ͠ͳ͍ʜ

12. Use struct func toggleSwitch() -> Bool { struct Switch {

    static var aSwitch = true } Switch.aSwitch = !Switch.aSwitch return Switch.aSwitch }

13. Cast var anyObject: AnyObject? = "WE ARE UPPERCASE" if anyObject

    is String { let string = anyObject as String println(string.lowercaseString + "?") } ৑௕ʁ

14. You can check, cast and bind in one line !

    if let string = anyObject as? String { println(string.lowercaseString + "?") }

15. Trailing closure func methodX(i: Int, function: ()->(String)) { function() }

    ! methodX(1, { () -> (String) in return "Do nothing" } ) ! methodX(1) { () -> (String) in return "Do nothing" }

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, +)

17. Nested function func setUpViews() { func setupBarButton() { // set

    up bar buttons } func setupRefreshControl() { // set up refresh control } setupBarButton() setupRefreshControl() } είʔϓΛอͬͨ··ɺॲཧΛߏ଄Խ͢Δ͜ͱ͕Ͱ͖Δ

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

19. Any Questions?