Swift ZHI - Open Source Swift App

Swift ZHI is a news reader app for ZhiHu Daily.

Presented at 7th July 2015 at CocoaHeads Brisbane meetup.

Transcript

1. Swift ZHI Open source App, written in Swift Swift Nicholas Tian #SwiftZHI github.com/NicholasTD07 https://github.com/NicholasTD07/Swift-ZHI
2. Frameworks • Quick and Nimble • Argo • Alamofire • Realm
3. Swift • Functional Programming • Fluent API • Type Inference
4. Objective-C App’s Demo • Refresh • Infinite Scroll • Detail View • Save News
5. isPoorDesign() // true
6. isPoorDesign() // true • Spaghetti Code | GOD Controller
7. isPoorDesign() // true • UI • Logic • Downloading • Decoding • Spaghetti Code | GOD Controller
8. isPoorDesign() // true • Spaghetti Code | GOD Controller
9. redesign() ->
10. redesign() -> • SwiftDailyAPI
11. redesign() -> • Swift-ZHI • SwiftDailyAPI
12. redesign() -> • Swift-ZHI • SwiftDailyAPI • Network - Alamofire
13. redesign() -> • Swift-ZHI • SwiftDailyAPI • JSON Decoding - Argo • Network - Alamofire
14. redesign() -> • Swift-ZHI • SwiftDailyAPI • JSON Decoding - Argo • Network - Alamofire • UI
15. redesign() -> • Swift-ZHI • SwiftDailyAPI • JSON Decoding - Argo • Network - Alamofire • Realm • UI
16. redesign() -> • Swift-ZHI • SwiftDailyAPI • JSON Decoding - Argo • Network - Alamofire • Realm • UI • BDD Testing - Quick • Matcher - Nimble
17. import Quick import Nimble class TableOfContentsSpec: QuickSpec { override func spec() { describe("the 'Documentation' directory") { it("has everything you need to get started") { let sections = Directory("Documentation").sections expect(sections).to(contain("Organized Tests with Quick Examples and Example Groups")) expect(sections).to(contain("Installing Quick")) } context("if it doesn't have what you're looking for") { it("needs to be updated") { let you = You(awesome: true) expect{you.submittedAnIssue}.toEventually(beTruthy()) } } } } }
18. class DailyAPISpecs: QuickSpec { override func spec() { let timeout: NSTimeInterval = 20 let api = DailyAPI(userAgent: "SwiftDailySpec") it("loads daily news for a date") { var daily: Daily? = nil let date = NSDate.dateFromString("20150525", format: "yyyyMMdd")! api.daily(forDate: date) { dailyFromAPI in daily = dailyFromAPI } expect(daily).toEventuallyNot(beNil(), timeout: timeout) expect(daily!.date).toEventually(equal(date), timeout: timeout) expect(daily!.news).toEventuallyNot(beEmpty(), timeout: timeout) } } }
19. Quick VS XCTest
20. Quick VS XCTest Quick * Better error message * fit - focus, xit - disable * More readable
21. Quick VS XCTest Quick * Better error message * fit - focus, xit - disable * More readable XCTest * Performance Test * UI Test
22. Functional JSON Decoding With Argo — SwiftDailyAPI
23. • Abstract Difference between imperative and functional programming?
24. • Abstract Difference between imperative and functional programming? • More about what than how
25. • Abstract Difference between imperative and functional programming? • WHAT THE HECK ARE THOSE OPERATORS • More about what than how
26. • Abstract Difference between imperative and functional programming? • WHAT THE HECK ARE THOSE OPERATORS • ARHHHHHHHHH.. - Nick’s first day with Argo • More about what than how
27. • Abstract Difference between imperative and functional programming? • WHAT THE HECK ARE THOSE OPERATORS • ARHHHHHHHHH.. - Nick’s first day with Argo • "Brain, offline." • More about what than how
28. Syntax highlighted code: Xcode -> TextEdit -> Keynote public struct NewsMeta { public let newsId: Int public let title: String public let imageURLs: [NSURL] } { "id": 12345, "title": "Title of the News", "images": ["http://image.url"] }
29. Syntax highlighted code: Xcode -> TextEdit -> Keynote public struct NewsMeta { public let newsId: Int public let title: String public let imageURLs: [NSURL] } static func decode(j: JSON) -> Decoded<NewsMeta> { return NewsMeta.create <^> j <| "id" <*> j <| "title" <*> j <|| "images" } { "id": 12345, "title": "Title of the News", "images": ["http://image.url"] }
30. Syntax highlighted code: Xcode -> TextEdit -> Keynote static func decode(j: JSON) -> Decoded<NewsMeta> { return NewsMeta.create <^> j <| "id" <*> j <| "title" <*> j <|| "images" } extension NewsMeta: Decodable { // Curried `init` private static func create(newsId: Int)(title: String) (imageURLs: [NSURL]) -> NewsMeta { return NewsMeta( newsId: newsId, title: title, imageURLs: imageURLs) } } { "id": 12345, "title": "Title of the News", "images": ["http://image.url"] }
31. return NewsMeta.create <^> (j <| "id") <*> j <| "title" <*> j <|| "images"
32. return NewsMeta.create <^> (j <| "id")
33. return NewsMeta.create <^> (j <| "id") public func <^><T, U>(f: T -> U, a: T?) -> U?
34. /** map a function over an optional value - If the value is .None, the function will not be evaluated and this will return .None - If the value is .Some, the function will be applied to the unwrapped value :param: f A transformation function from type T to type U :param: a A value of type Optional<T> :returns: A value of type Optional<U> */ return NewsMeta.create <^> (j <| "id") public func <^><T, U>(f: T -> U, a: T?) -> U?
35. /** map a function over an optional value - If the value is .None, the function will not be evaluated and this will return .None - If the value is .Some, the function will be applied to the unwrapped value :param: f A transformation function from type T to type U :param: a A value of type Optional<T> :returns: A value of type Optional<U> */ return NewsMeta.create <^> (j <| "id") public func <^><T, U>(f: T -> U, a: T?) -> U? Q: What’s the type of U in this case?
36. /** map a function over an optional value - If the value is .None, the function will not be evaluated and this will return .None - If the value is .Some, the function will be applied to the unwrapped value :param: f A transformation function from type T to type U :param: a A value of type Optional<T> :returns: A value of type Optional<U> */ return NewsMeta.create <^> (j <| "id") public func <^><T, U>(f: T -> U, a: T?) -> U? A: Partially Applied create function Q: What’s the type of U in this case?
37. return NewsMeta.create <^> (j <| "id") public func <^><T, U>(f: T -> U, a: T?) -> U? A: Partially Applied create function Q: What’s the type of U in this case? (title: String)(imageURLs: [NSURL]) -> NewsMeta
38. return NewsMeta.create <^> (j <| "id") <*> j <| "title" <*> j <|| "images"
39. return NewsMeta.create <^> (j <| "id") <*> j <| "title" <*> j <|| "images" public func <*><T, U>(f: (T -> U)?, a: T?) -> U? public func <^><T, U>(f: T -> U, a: T?) -> U?
40. return NewsMeta.create <^> (j <| "id") <*> j <| "title" <*> j <|| "images" /** apply an optional function to an optional value - If either the value or the function are .None, the function will not be evaluated and this will return .None - If both the value and the function are .Some, the function will be applied to the unwrapped value :param: f An optional transformation function from type T to type U :param: a A value of type Optional<T> :returns: A value of type Optional<U> */ public func <*><T, U>(f: (T -> U)?, a: T?) -> U? public func <^><T, U>(f: T -> U, a: T?) -> U?
41. /** flatMap a function over an optional value (left associative) - If the value is .None, the function will not be evaluated and this will return .None - If the value is .Some, the function will be applied to the unwrapped value :param: f A transformation function from type T to type Optional<U> :param: a A value of type Optional<T> :returns: A value of type Optional<U> */ public func >>-<T, U>(a: T?, f: T -> U?) -> U?
42. Syntax highlighted code: Xcode -> TextEdit -> Keynote
43. Syntax highlighted code: Xcode -> TextEdit -> Keynote public struct News { public let newsId: Int public let title: String public let body: String public let cssURLs: [NSURL] public let imageURL: NSURL public let imageSourceText: String public let shareURL: NSURL }
44. Syntax highlighted code: Xcode -> TextEdit -> Keynote public struct News { public let newsId: Int public let title: String public let body: String public let cssURLs: [NSURL] public let imageURL: NSURL public let imageSourceText: String public let shareURL: NSURL } public static func decode(j: JSON) -> Decoded<News> { return News.create <^> j <| "id" <*> j <| "title" <*> j <| "body" <*> j <|| "css" <*> j <| "image" <*> j <| "image_source" <*> j <| "share_url" }
45. extension NSURL: Decodable { public static func decode(j: JSON) -> Decoded<NSURL> { switch(j) { case let .String(s): return Decoded<NSURL>.fromOptional(NSURL(string: s)) default: return .TypeMismatch("\(j) is not a NSURL.") } } }
46. extension NSURL: Decodable { public static func decode(j: JSON) -> Decoded<NSURL> { switch(j) { case let .String(s): return Decoded<NSURL>.fromOptional(NSURL(string: s)) default: return .TypeMismatch("\(j) is not a NSURL.") } } } 20150707
47. extension NSURL: Decodable { public static func decode(j: JSON) -> Decoded<NSURL> { switch(j) { case let .String(s): return Decoded<NSURL>.fromOptional(NSURL(string: s)) default: return .TypeMismatch("\(j) is not a NSURL.") } } } 20150707 public func toNSDate(format: String)(dateString: String) -> Decoded<NSDate> { return .fromOptional(NSDate.dateFromString(dateString, format: format)) }
48. extension NSURL: Decodable { public static func decode(j: JSON) -> Decoded<NSURL> { switch(j) { case let .String(s): return Decoded<NSURL>.fromOptional(NSURL(string: s)) default: return .TypeMismatch("\(j) is not a NSURL.") } } } 20150707 public func toNSDate(format: String)(dateString: String) -> Decoded<NSDate> { return .fromOptional(NSDate.dateFromString(dateString, format: format)) } <^> ((j <| "date") >>- toNSDate("yyyyMMdd")) create
49. extension NSURL: Decodable { public static func decode(j: JSON) -> Decoded<NSURL> { switch(j) { case let .String(s): return Decoded<NSURL>.fromOptional(NSURL(string: s)) default: return .TypeMismatch("\(j) is not a NSURL.") } } } 20150707 public func toNSDate(format: String)(dateString: String) -> Decoded<NSDate> { return .fromOptional(NSDate.dateFromString(dateString, format: format)) } <^> ((j <| "date") >>- toNSDate("yyyyMMdd")) step 1 create
50. extension NSURL: Decodable { public static func decode(j: JSON) -> Decoded<NSURL> { switch(j) { case let .String(s): return Decoded<NSURL>.fromOptional(NSURL(string: s)) default: return .TypeMismatch("\(j) is not a NSURL.") } } } public func toNSDate(format: String)(dateString: String) -> Decoded<NSDate> { return .fromOptional(NSDate.dateFromString(dateString, format: format)) } <^> ((j <| "date") >>- toNSDate("yyyyMMdd")) step 1 "20150707" create
51. extension NSURL: Decodable { public static func decode(j: JSON) -> Decoded<NSURL> { switch(j) { case let .String(s): return Decoded<NSURL>.fromOptional(NSURL(string: s)) default: return .TypeMismatch("\(j) is not a NSURL.") } } } public func toNSDate(format: String)(dateString: String) -> Decoded<NSDate> { return .fromOptional(NSDate.dateFromString(dateString, format: format)) } step 1 step 2 <^> ((j <| "date") >>- toNSDate("yyyyMMdd")) "20150525" NSDate.dateFromString("20150707", format: "yyyyMMdd") create
52. extension NSURL: Decodable { public static func decode(j: JSON) -> Decoded<NSURL> { switch(j) { case let .String(s): return Decoded<NSURL>.fromOptional(NSURL(string: s)) default: return .TypeMismatch("\(j) is not a NSURL.") } } } public func toNSDate(format: String)(dateString: String) -> Decoded<NSDate> { return .fromOptional(NSDate.dateFromString(dateString, format: format)) } step 3 step 1 step 2 <^> ((j <| "date") >>- toNSDate("yyyyMMdd")) "20150525" NSDate.dateFromString("20150707", format: "yyyyMMdd") create
53. Network Operations with Alamofire
54. Network Operations with Alamofire "NOT FUNCTIONAL PROGRAMMING, THANK GOD!"
55. Alamofire.request(.GET, URLString: "http://httpbin.org/ get", parameters: ["foo": "bar"]) .response { (request, response, data, error) in print(request) print(response) print(error) } Fluent API with Swift
56. Alamofire.request(.GET, URLString: "http://httpbin.org/ get", parameters: ["foo": "bar"]) .response { (request, response, data, error) in print(request) print(response) print(error) } Fluent API with Swift Alamofire.request(.GET, URLString: "http://httpbin.org/ get", parameters: ["foo": "bar"]) .validate(statusCode: 200..<300) .validate(contentType: ["application/json"]) .response { (_, _, _, error) in print(error) }
57. public func latestDaily(completionHandler: (LatestDailyNews?) -> Void) -> Request { return manager.request(DailyRouter.LastestDaily) .responseJSON { (request, response, JSON, error) in completionHandler(JSON >>- decode) } } public func dailyNews(forDate date: NSDate, completionHandler: (DailyNews?) -> Void) -> Request { return manager.request(DailyRouter.DailyNews(forDate: date)) .responseJSON { (request, response, JSON, error) in completionHandler(JSON >>- decode) } } public func news(newsId: Int, completionHandler: (News?) -> Void) -> Request { return manager.request(DailyRouter.News(newsId: newsId)) .responseJSON { (request, response, JSON, error) in completionHandler(JSON >>- decode) } }
58. The Power of Generics
59. public func latestDaily(completionHandler: (LatestDailyNews?) -> Void) -> Request { return manager.request(DailyRouter.LastestDaily) .responseJSON { (request, response, JSON, error) in completionHandler(JSON >>- decode) } } public func dailyNews(forDate date: NSDate, completionHandler: (DailyNews?) -> Void) -> Request { return manager.request(DailyRouter.DailyNews(forDate: date)) .responseJSON { (request, response, JSON, error) in completionHandler(JSON >>- decode) } } public func news(newsId: Int, completionHandler: (News?) -> Void) -> Request { return manager.request(DailyRouter.News(newsId: newsId)) .responseJSON { (request, response, JSON, error) in completionHandler(JSON >>- decode) } }
60. public func latestDaily(completionHandler: (LatestDailyNews?) -> Void) -> Request { return manager.request(DailyRouter.LastestDaily) .responseJSON { (request, response, JSON, error) in completionHandler(JSON >>- decode) } } public func dailyNews(forDate date: NSDate, completionHandler: (DailyNews?) -> Void) -> Request { return manager.request(DailyRouter.DailyNews(forDate: date)) .responseJSON { (request, response, JSON, error) in completionHandler(JSON >>- decode) } } public func news(newsId: Int, completionHandler: (News?) -> Void) -> Request { return manager.request(URLRequest) .responseJSON { (request, response, JSON, error) in completionHandler(JSON >>- decode) } }
61. private final func request<T: Decodable where T == T.DecodedType>(URLRequest: URLRequestConvertible, completionHandler: T? -> Void) -> Request { return manager.request(URLRequest) .responseJSON { (request, response, JSON, error) in completionHandler(JSON >>- decode) } }
62. public func latestDaily(completionHandler: (LatestDailyNews?) -> Void) -> Request { return request(DailyRouter.LastestDaily, completionHandler: completionHandler) } public func dailyNews(forDate date: NSDate, completionHandler: (DailyNews?) -> Void) -> Request { return request(DailyRouter.DailyNews(forDate: date), completionHandler: completionHandler) } public func news(newsId: Int, completionHandler: (News?) -> Void) -> Request { return request(DailyRouter.News(newsId: newsId), completionHandler: completionHandler) } private final func request<T: Decodable where T == T.DecodedType>(URLRequest: URLRequestConvertible, completionHandler: T? -> Void) -> Request { return manager.request(URLRequest) .responseJSON { (request, response, JSON, error) in completionHandler(JSON >>- decode) } } private final func request<T: Decodable where T == T.DecodedType>(URLRequest: URLRequestConvertible, completionHandler: T? -> Void) -> Request { return manager.request(URLRequest) .responseJSON { (request, response, JSON, error) in completionHandler(JSON >>- decode) } }
63. Type Inference is Awesome.
64. public final func longComments(newsId: Int, commentsHandler: (Comments?) -> Void) -> Request { return request(DailyRouter.LongComments(newsId: newsId), completionHandler: commentsHandler) } private final func request<T: Decodable where T == T.DecodedType>(URLRequest: URLRequestConvertible, completionHandler: T? -> Void) -> Request { return manager .request(URLRequest) .responseJSON { (request, response, JSON, error) in completionHandler(JSON >>- decode) } }
65. private final func request<T: Decodable where T == T.DecodedType>(URLRequest: URLRequestConvertible, completionHandler: T -> Void) -> Request { return manager .request(URLRequest) .responseJSON { (request, response, JSON, error) in let decoded: T? = JSON >>- decode if let decoded = decoded { completionHandler(decoded) } } Handlers take non-nil values only public final func longComments(newsId: Int, commentsHandler: (Comments) -> Void) -> Request { return request(DailyRouter.LongComments(newsId: newsId), completionHandler: commentsHandler) }
66. class DailyAPISpecs: QuickSpec { override func spec() { let timeout: NSTimeInterval = 20 let api = DailyAPI(userAgent: "SwiftDailySpec") it("loads daily news for a date") { var daily: Daily? = nil let date = NSDate.dateFromString("20150525", format: "yyyyMMdd")! api.daily(forDate: date) { dailyFromAPI in daily = dailyFromAPI } expect(daily).toEventuallyNot(beNil(), timeout: timeout) expect(daily!.date).toEventually(equal(date), timeout: timeout) expect(daily!.news).toEventuallyNot(beEmpty(), timeout: timeout) } } }
67. class DailyAPISpecs: QuickSpec { override func spec() { let timeout: NSTimeInterval = 20 let api = DailyAPI(userAgent: "SwiftDailySpec") it("loads daily news for a date") { var daily: Daily? = nil let date = NSDate.dateFromString("20150525", format: "yyyyMMdd")! api.daily(forDate: date) { dailyFromAPI in daily = dailyFromAPI } expect(daily).toEventuallyNot(beNil(), timeout: timeout) expect(daily!.date).toEventually(equal(date), timeout: timeout) expect(daily!.news).toEventuallyNot(beEmpty(), timeout: timeout) } } }
69. Model Definition in Realm
70. public class NewsMetaObject: Object { dynamic public var newsId: Int = 0 dynamic public var title: String = "" } public class DailyObject: Object { dynamic public var dateHash: Int = 0 dynamic public var date: NSDate = NSDate() public let news = List<NewsMetaObject>() }
71. public class DailyObject: Object { dynamic public var dateHash: Int = 0 dynamic public var date: NSDate = NSDate() public let news = List<NewsMetaObject>() override public static func primaryKey() -> String? { return "dateHash" } override public static func indexedProperties() -> [String] { return ["date", "dateHash"] } }
72. Adding Objects in Realm
73. private func addOrUpdateObject(object: Object, toRealm realm: Realm = defaultRealm()) { realm.write { realm.add(object, update: true) } }
74. Fetching Objects in Realm
75. public class DailyRealmStore { let realm = defaultRealm() public func dailyAtDate(date: NSDate) -> DailyObject? { let results = realm.objects(DailyObject).filter("dateHash == \ (date.hash)") return results.first } public func newsWithId(newsId: Int) -> NewsObject? { let results = realm.objects(NewsObject).filter("newsId == \(newsId)") return results.first } }
76. Notification in Realm
77. extension RealmDailyTableViewController { override func viewDidLoad() { super.viewDidLoad() token = defaultRealm().addNotificationBlock { (_, _) in self.tableView.reloadData() } } }
78. Swift 1.2 -> 2.0 • API is better typed, better named • guard • @testable
79. @testable import SwiftDailyAPI class Xcode7PlusSwift2: QuickSpec { override func spec() { describe("Xcode7 + Swift 2") { it("is AWESOME!") { Daily(date: NSDate(), news: []) } } } } @testable
80. public struct Daily { public let date: NSDate public let news: [NewsMeta] } extension Daily { public init(_ latestDaily: LatestDaily) { date = latestDaily.date news = latestDaily.news } } extension Daily: Decodable { private static func create(date: NSDate)(news: [NewsMeta]) -> Daily { return Daily(date: date, news: news) } public static func decode(j: JSON) -> Decoded<Daily> { return Daily.create <^> ((j <| "date") >>- toNSDate(DailyConstants.dateFormat)) <*> j <|| "stories" } }
81. Swift 2.0 -> 1.2 override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) { if segue.identifier == "showNews/Realm" { guard let indexPath = tableView.indexPathForSelectedRow else { return } guard let newsMeta = newsMetaAtIndexPath(indexPath) else { return } guard let vc = segue.destinationViewController as? RealmNewsViewController else { return } vc.store = store vc.newsId = newsMeta.newsId } }
82. Swift 2.0 -> 1.2 override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) { if segue.identifier == "showNews/Realm" { if let indexPath = tableView.indexPathForSelectedRow(), let newsMeta = newsMetaAtIndexPath(indexPath), let vc = segue.destinationViewController as? RealmNewsViewController { vc.store = store vc.newsId = newsMeta.newsId } } }
83. Swift ZHI Nicholas Tian