Any型をprotocolにキャストする時に 気をつけた方がいい話

Transcript

1. AnyܕΛprotocolʹΩϟετ͢Δ࣌ʹ ؾΛ͚ͭͨํ͕͍͍࿩ 2019/5/21 ͋Δ͋ΔLT vol4 PKPK-Carnage(Tomosuke Okada) 1
2. About me • iOSྺ2೥ͪΐͬͱ • Qiita → @PKPK-Carnage • Github → PKPK-Carnage • Twitter → @PKPK-Carnage
3. ͦΜͳͷ؆୯͡ΌΜ 3
4. Any as? Protocol 4
5. ྫɿNotification 5 protocol Animal {} struct Dog: Animal {}
6. ྫɿNotification 6 class HogeClass { func postNotification() { // DogΛૹΔ NotificationCenter.default.post( name: .init("Animal"), object: Dog() ) } }
7. ྫɿNotification 7 class FugaClass { init() { NotificationCenter.default.addObserver( self, selector: #selector(self.didReceivedNotification(_:)), name: .init("Animal"), object: nil ) } @objc func didReceivedNotification(_ notification: Notification) { } }
8. ྫɿNotification 8 @objc func didReceivedNotification(_ notification: Notification) { // notification.objectͷத਎Λग़ྗ͢Δ print("\(String(describing: notification.object))") // notification.objectΛAnimal(Protocol)ʹΩϟετͨ͠ޙͷத਎Λग़ྗ͢Δ let animal = notification.object as? Animal print("\(String(describing: animal))") } Optional(__lldb_expr_11.Dog()) nil
10. SR-3871 10
11. SR-3871 • Swiftͷstructʹas AnyObjectΛߦͬͯɺAnyܕʹ֨ೲͨ࣌͠ʹɺ Protocol΁ͷ४ڌ൑ఆ͕ߦ͑ͳ͘ͳΔόά͕͋Δ • AnyܕͷΦϒδΣΫτʹas AnyObjectΛߦ͑͹ɺͪΌΜͱProtocol΁ ͷ४ڌ൑ఆ͕ߦ͑ΔΑ͏ʹͳΔɻ 11
12. ࣮ࡍʹ΍ͬͯΈͨ 12 @objc func didReceivedNotification(_ notification: Notification) { // notification.objectͷத਎Λग़ྗ͢Δ print("\(String(describing: notification.object))") // notification.objectΛAnimal(Protocol)ʹΩϟετͨ͠ޙͷத਎Λग़ྗ͢Δ let animal = notification.object as? Animal print("\(String(describing: animal))") }
13. ࣮ࡍʹ΍ͬͯΈͨ 13 @objc func didReceivedNotification(_ notification: Notification) { // notification.objectͷத਎Λग़ྗ͢Δ print("\(String(describing: notification.object))") // notification.objectΛAnimal(Protocol)ʹΩϟετͨ͠ޙͷத਎Λग़ྗ͢Δ let animal = (notification.object as AnyObject) as? Animal print("\(String(describing: animal))") }
14. ࣮ࡍʹ΍ͬͯΈͨ 14 Optional(__lldb_expr_11.Dog()) Optional(__lldb_expr_11.Dog()) @objc func didReceivedNotification(_ notification: Notification) { // notification.objectͷத਎Λग़ྗ͢Δ print("\(String(describing: notification.object))") // notification.objectΛAnimal(Protocol)ʹΩϟετͨ͠ޙͷத਎Λग़ྗ͢Δ let animal = (notification.object as AnyObject) as? Animal print("\(String(describing: animal))") }
16. Qiitaॻ͖·ͨ͠ 16 https://qiita.com/PKPK-Carnage/items/5e2eda7735aa24f807a9
17. ͓ΘΓ 17