Design patterns in Swift Vol. 0

Transcript

1. Design Patterns
 in 
 Swift John Lin Vol 0
2. ॄኄੋDesign patterns? • Design patterns = ઃܭ໛ࣜɻ • ֤छೈᱪதৗݟతՍߏɼ㢨ଞ၇औҰݸ໊ࣈɻṜᒬࢠ ࠽ํศ౼࿦ɻ • औៃࣗݐஙላత໊ࣈɻ
3. ࠷ஶ໊తઃܭ໛ࣜ၇ • Design Patterns: Elements of Reusable Object-Oriented Software 
 BY Erich Gamma , Richard Helm , Ralph Johnson , John Vlissides ؆᜝ GoF(gang of four) ࢛ਓ㢨ɻ • ཫ໘ሜྃ23 छৗݟతC++෺݅ಋ޲໛ ࣜɻ
4. ઃܭ໛ࣜత໰୊ • Ṝຊॻੋඳड़C++࿨ Smalltalk தৗݟత໰୊࿨ղܾ తํ๏ɻ • ୠੋሣଖଞޠݴိ㘸ɼṜࠣղܾํ๏҃ڐ༗ߋ޷తղ ܾํ๏ɻ
5. Singleton • ੔ݸఔࣜཫ୞ೳ༗Ұݸመᱪ(instance)ɻ • ৗ༻ိᙛ࡞ࢿݯ؅ཧऀ(manager)ɻ • መ࡞࣌धཁߟྀଟࣥߦॹ࣌త㐫گɻ
6. @interface Singleton : NSObject @end @implementation Singleton + (instancetype)sharedInstance { static Singleton *sharedInstance = nil; static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ sharedInstance = [[Singleton alloc] init]; }); return sharedInstance; } @end
7. error: 'dispatch_once_t' is unavailable in Swift: Use lazily initialized globals instead static var onceToken: dispatch_once_t = 0 ^~~~~~~~~~~~~~~
8. class Singleton { static let sharedInstance = Singleton() }
9. Iterator • భ୅ث • ༻ိଘऔҰݸ༰ث㚎తݩૉ • ෆधཁ࢖༻ index
10. for i in 1...10 { print(i) } for c in "hello world".characters { print(c) }
11. Swift తభ୅ث Protocol
 IteratorProtocol • ੋҰݸ Protocol • ୞༗ҰݸඞཁతവᏐ next() • ᙛ༗ԼҰݸݩૉ࣌ɼճၚಹݸݩૉ • ᔒ༗ԼҰݸݩૉత࣌ީɼճၚ nil
12. Swift తجૅభ୅ث
 AnyIterator • ੋҰݸ Struct • আྃభ୅೭֎ؐ༗ଖଞతޭೳɻ
13. var s = "" let iter = AnyIterator<String> { let c = s.characters.count % 2 == 0 ? "5" : "6" s = s + c return s.characters.count > 10 ? nil : s } for c in iter { print(c) } /* 5 56 … 565656565 5656565656 */
14. var s = "" let iter = AnyIterator<String> { let c = s.characters.count % 2 == 0 ? "5" : "6" s = s + c return s.characters.count > 10 ? nil : s } for c in iter.filter({ $0.characters.count % 2 == 0 }) { print(c) } /* 56 5656 565656 56565656 5656565656 */
15. var s = "" let iter = AnyIterator<String> { let c = s.characters.count % 2 == 0 ? "5" : "6" s = s + c return s.characters.count > 10 ? nil : s } for (idx,c) in iter.enumerated() { print("\(idx):\(c)") } /* 0:5 1:56 2:565 … 8:565656565 9:5656565656 */
16. ᩋ㟬తClass ໵ೳඃభ୅ • ៺ঝ IteratorProtocol ࿨ Sequence • typealias Element = <ཁճၚతType> • ఆٛ next()
17. class PPAP : Sequence, IteratorProtocol { typealias Element = String let stuffs = [ "APPLEPEN", "PINEAPPLEPEN", "PENPINEAPPLEAPPLEPEN"] var idx = 0 func next()-> String? { defer {idx += 1} guard idx < stuffs.count else { return nil } return stuffs[idx] } } let ppap = PPAP() for p in ppap { print(p) }
18. class PPAP : Sequence, IteratorProtocol { typealias Element = String let stuffs = [ "APPLEPEN", "PINEAPPLEPEN", "PENPINEAPPLEAPPLEPEN"] var idx = 0 func next()-> String? { defer {idx += 1} guard idx < stuffs.count else { return nil } return stuffs[idx] } } let ppap = PPAP() for p in ppap { print(p) } /* APPLEPEN PINEAPPLEPEN PENPINEAPPLEAPPLEPEN */
19. let ppap = PPAP() for p in ppap { print(p) }
20. Q&A