如果您确实想使用 UserDefaults 保存数据,最简单的方法是使用一个类并使其符合 NSCoding。关于您的全局 var domainSchemas,我建议使用单例或扩展 UserDefaults 并为其创建一个计算属性:
class DomainSchema: NSObject, NSCoding {
var domain: String
var schema: String
init(domain: String, schema: String) {
self.domain = domain
self.schema = schema
}
required init(coder decoder: NSCoder) {
self.domain = decoder.decodeObject(forKey: "domain") as? String ?? ""
self.schema = decoder.decodeObject(forKey: "schema") as? String ?? ""
}
func encode(with coder: NSCoder) {
coder.encode(domain, forKey: "domain")
coder.encode(schema, forKey: "schema")
}
}
extension UserDefaults {
var domainSchemas: [DomainSchema] {
get {
guard let data = UserDefaults.standard.data(forKey: "domainSchemas") else { return [] }
return (try? NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(data)) as? [DomainSchema] ?? []
}
set {
UserDefaults.standard.set(try? NSKeyedArchiver.archivedData(withRootObject: newValue, requiringSecureCoding: false), forKey: "domainSchemas")
}
}
}
Usage:
UserDefaults.standard.domainSchemas = [.init(domain: "a", schema: "b"), .init(domain: "c", schema: "d")]
UserDefaults.standard.domainSchemas // [{NSObject, domain "a", schema "b"}, {NSObject, domain "c", schema "d"}]
如果您更喜欢使用 Codable 方法来使用 UserDefaults 保存数据:
struct DomainSchema: Codable {
var domain: String
var schema: String
init(domain: String, schema: String) {
self.domain = domain
self.schema = schema
}
}
extension UserDefaults {
var domainSchemas: [DomainSchema] {
get {
guard let data = UserDefaults.standard.data(forKey: "domainSchemas") else { return [] }
return (try? PropertyListDecoder().decode([DomainSchema].self, from: data)) ?? []
}
set {
UserDefaults.standard.set(try? PropertyListEncoder().encode(newValue), forKey: "domainSchemas")
}
}
}
Usage:
UserDefaults.standard.domainSchemas = [.init(domain: "a", schema: "b"), .init(domain: "c", schema: "d")]
UserDefaults.standard.domainSchemas // [{domain "a", schema "b"}, {domain "c", schema "d"}]
我认为最好的选择是不使用 UserDefaults,创建一个单例“共享实例”,在那里声明一个 domainSchemas 属性并将 json 数据保存在应用程序支持目录的子目录中:
extension URL {
static var domainSchemas: URL {
let applicationSupport = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask).first!
let bundleID = Bundle.main.bundleIdentifier ?? "company name"
let subDirectory = applicationSupport.appendingPathComponent(bundleID, isDirectory: true)
try? FileManager.default.createDirectory(at: subDirectory, withIntermediateDirectories: true, attributes: nil)
return subDirectory.appendingPathComponent("domainSchemas.json")
}
}
class Shared {
static let instance = Shared()
private init() { }
var domainSchemas: [DomainSchema] {
get {
guard let data = try? Data(contentsOf: .domainSchemas) else { return [] }
return (try? JSONDecoder().decode([DomainSchema].self, from: data)) ?? []
}
set {
try? JSONEncoder().encode(newValue).write(to: .domainSchemas)
}
}
}
Usage:
Shared.instance.domainSchemas = [.init(domain: "a", schema: "b"), .init(domain: "c", schema: "d")]
Shared.instance.domainSchemas // [{domain "a", schema "b"}, {domain "c", schema "d"}]