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Advanced Usecase for Codable
Daiki Matsudate / @d_date
2018/01/24
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Daiki Matsudate
@d_date
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Tokyo
2018/3/1 - 3
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Codable
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typealias Codable = Encodable & Decodable
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typealias Codable = Encodable & Decodable
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No content
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Encodable
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let data = """
{
"id": 1,
"to": “sample",
"message": “ੜ͓ΊͰͱ͏͍͟͝·͢!"
}
""".data(using: .utf8)!
do {
//Decode
let model = try JSONDecoder().decode(Model.self, from: data)
//Encode
let encodedData = try JSONEncoder().encode(model) // Data
} catch {
print(error)
}
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Usecases of Encodable
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Case 1. Offline Cacheing
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Server
Cache
Application
Online
Offline
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static func save(response: Response, fileName: String)
throws {
guard let fileUrl = FileCacheHandler.filePath(fileName: fileName,
pagination: response.header) else {
throw CacheError.cachesPathNotExist
}
do {
let data = try JSONEncoder().encode(response.body)
let directoryUrl = fileUrl.deletingLastPathComponent()
if !FileManager.default.fileExists(atPath: directoryUrl.path) {
try FileManager.default.createDirectory(at: directoryUrl,
withIntermediateDirectories: true, attributes: nil)
}
try data.write(to: fileUrl)
print("saved: \(fileUrl)")
} catch {
print(error.localizedDescription)
throw error
}
}
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static func save(response: Response, fileName: String)
throws {
guard let fileUrl = FileCacheHandler.filePath(fileName: fileName,
pagination: response.header) else {
throw CacheError.cachesPathNotExist
}
do {
let data = try JSONEncoder().encode(response.body)
let directoryUrl = fileUrl.deletingLastPathComponent()
if !FileManager.default.fileExists(atPath: directoryUrl.path) {
try FileManager.default.createDirectory(at: directoryUrl,
withIntermediateDirectories: true, attributes: nil)
}
try data.write(to: fileUrl)
print("saved: \(fileUrl)")
} catch {
print(error.localizedDescription)
throw error
}
}
Encoding Json to data
Write data to local path
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func load(fileName: String) -> Observable> {
return Observable.create({ (observer) -> Disposable in
guard let fileUrl = FileCacheHandler.filePath(fileName: fileName) else {
observer.onError(CacheError.cachesPathNotExist)
return Disposables.create()
}
guard FileManager.default.fileExists(atPath: fileUrl.path) else {
observer.onError(CacheError.cacheNotExist)
return Disposables.create()
}
do {
let data = try Data(contentsOf: fileUrl)
let model = try JSONDecoder().decode(T.self, from: data)
print("loaded: \(fileUrl)")
let response = Response(statusCode: 200, header: [:], body: model)
observer.onNext(response)
} catch {
observer.onError(error)
}
return Disposables.create()
})
}
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func load(fileName: String) -> Observable> {
return Observable.create({ (observer) -> Disposable in
guard let fileUrl = FileCacheHandler.filePath(fileName: fileName) else {
observer.onError(CacheError.cachesPathNotExist)
return Disposables.create()
}
guard FileManager.default.fileExists(atPath: fileUrl.path) else {
observer.onError(CacheError.cacheNotExist)
return Disposables.create()
}
do {
let data = try Data(contentsOf: fileUrl)
let model = try JSONDecoder().decode(T.self, from: data)
print("loaded: \(fileUrl)")
let response = Response(statusCode: 200, header: [:], body: model)
observer.onNext(response)
} catch {
observer.onError(error)
}
return Disposables.create()
})
}
Load data from local path
Decode data
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Case 2. Save token into Keychain
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func signUp() -> Single {
return useCase.signUp()
.map({ (user) -> AuthenticatedUserModel in
let data = try JSONEncoder().encode((user))
AccessToken.set(data: data)
})
}
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func signUp() -> Single {
return useCase.signUp()
.map({ (user) -> AuthenticatedUserModel in
let data = try JSONEncoder().encode((user))
AccessToken.set(data: data)
})
}
Saving data in Keychain
Encoding object into data
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var currentUser: AuthenticatedUserModel? {
do {
guard let data = AccessToken.getData() else { return nil }
return try JSONDecoder().decode(AuthenticatedUserModel.self,
from: data)
} catch {
return nil
}
}
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var currentUser: AuthenticatedUserModel? {
do {
guard let data = AccessToken.getData() else { return nil }
return try JSONDecoder().decode(AuthenticatedUserModel.self,
from: data)
} catch {
return nil
}
}
Get data from keychain
Decoding data into Model
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Recap
• In general, Codable is very useful for decoding json into your
model
• Sometimes Encodable is also useful to store your model as
data
• We should think about DB is needed for your app
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Enjoy! Codable