[英]How to save a swift struct to file
我想為我的應用程序的(非常簡單的)model 使用結構。
但是NSKeyedArchiver
只接受對象(擴展NSObjects
)。
有什么好方法可以將結構保存到文件中嗎?
我有時使用的一種非常簡單的方法。 您需要編寫的代碼數量不超過類/ NSCoding方案。
首先導入偉大的SwiftyJSON庫。
struct Starship {
let name: String
let warpSpeed: Bool
let captain: String?
init(name: String, warpSpeed: Bool, captain: String? = nil) {
self.name = name
self.warpSpeed = warpSpeed
self.captain = captain
}
}
struct Starship {
let name: String
let warpSpeed: Bool
let captain: String?
init(name: String, warpSpeed: Bool, captain: String? = nil) {
self.name = name
self.warpSpeed = warpSpeed
self.captain = captain
}
init?(json: JSON) {
guard let
name = json["name"].string,
warpSpeed = json["warpSpeed"].bool
else { return nil }
self.name = name
self.warpSpeed = warpSpeed
self.captain = json["captain"].string
}
var asJSON: JSON {
var json: JSON = [:]
json["name"].string = name
json["warpSpeed"].bool = warpSpeed
json["captain"].string = captain
return json
}
}
let enterprise = Starship(name: "Enteriprise D", warpSpeed: true, captain: "JeanLuc Picard")
let json = enterprise.asJSON
let data = try! json.rawData()
// save data to file and reload it
let newJson = JSON(data: data)
let ship = Starship(json: newJson)
ship?.name // "Enterprise D"
Swift 5+ 的更新解決方案
struct Starship: Codable { // Add this
let name: String
let warpSpeed: Bool
let captain: String?
init(name: String, warpSpeed: Bool, captain: String? = nil) {
self.name = name
self.warpSpeed = warpSpeed
self.captain = captain
}
}
var data: Starship
func readFromFile(filePathURL: URL) throws {
let readData = try Data(contentsOf: filePathURL)
self.data = try JSONDecoder().decode(Starship.self, from: readData)
}
func writeToFile(filePathURL: URL) throws {
let jsonData = try JSONEncoder().encode(self.data)
try jsonData.write(to: filePathURL)
}
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