如何解决如何将对象数组保存到 NSUserDefaults?
我想知道如何将一组对象保存到 NSUserDefault。我已经阅读了有关对数据数组进行编码的文章,但不确定该过程是如何工作的。
这是我的数组:
//EventData class with EventDataArray
class EventData {
static var EventDataArray: [EventModel] = []
}
这是我的数据模型:
struct EventModel {
var id = UUID()
var eventName: String
var fromTime: Date
var toTime: Date
var fromTimeString: String
var toTimeString: String
var color: UIColor
}
编辑:更新的数组类
class EventData: Codable {
static var EventDataArray: [EventModel] = []
}
我将不胜感激任何有关该主题的建议!
解决方法
要在 UserDefaults 中保存结构,您需要先对其进行编码,以便能够将其保存为数据。所以你需要让你的自定义结构符合 Codable:
struct Event: Codable {
let id: UUID
let name: String
let start,end: Date
let fromTime,toTime: String
let color: Color
init(id: UUID = .init(),name: String,start: Date,end: Date,fromTime: String,toTime: String,color: Color) {
self.id = id
self.name = name
self.start = start
self.end = end
self.fromTime = fromTime
self.toTime = toTime
self.color = color
}
}
请注意,您不能使 UIColor 符合 Codable,但您可以创建自定义颜色结构:
struct Color: Codable {
let (r,g,b,a): (CGFloat,CGFloat,CGFloat)
}
extension Color {
init?(_ uiColor: UIColor) {
var (r,CGFloat) = (0,0)
guard uiColor.getRed(&r,green: &g,blue: &b,alpha: &a) else { return nil }
self.init(r: r,g: g,b: b,a: a)
}
var color: UIColor { .init(red: r,green: g,blue: b,alpha: a) }
}
extension UIColor {
convenience init(_ color: Color) {
self.init(red: color.r,green: color.g,blue: color.b,alpha: color.a)
}
var color: Color? { Color(self) }
}
关于你的类,你也可以让它符合 Codable 或继承自 NSObject 并符合 NSCoding:
class Events: NSObject,NSCoding {
private override init() { }
static var shared = Events()
var events: [Event] = []
required init(coder decoder: NSCoder) {
events = try! JSONDecoder().decode([Event].self,from: decoder.decodeData()!)
}
func encode(with coder: NSCoder) {
try! coder.encode(JSONEncoder().encode(events))
}
}
游乐场测试:
Events.shared.events = [.init(name: "a",start: Date(),end: Date(),fromTime: "fromTime",toTime: "toTime",color: .init(r: 0,g: 0,b: 1,a: 1)),.init(name: "b",fromTime: "fromTimeB",toTime: "toTimeB",g: 1,b: 0,a: 1))]
print(Events.shared.events)
let data = try! NSKeyedArchiver.archivedData(withRootObject: Events.shared,requiringSecureCoding: false)
UserDefaults.standard.set(data,forKey: "events")
Events.shared.events = []
print(Events.shared.events)
let loadedData = UserDefaults.standard.data(forKey: "events")!
Events.shared = try! NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(loadedData) as! Events
print(Events.shared.events)
这将打印
[事件(编号:C7D9475B-773E-4272-84CC-56CAEAA73D0C,名称:“a”,开始:2021-01-26 05:17:30 +0000,结束:2021-01-26 05:17: 30 +0000,color: Color(r: 0.0,g: 0.0,b: 1.0,a: 1.0)),Event(id: 0BEA4225-2F63-4EEB-AF10- F3EF4C84D050,名称:“b”,开始:2021-01-26 05:17:30 +0000,结束:2021-01-26 05:17:30 +0000,fromTime:“fromTimeB”,toTime:“toTimeB”,颜色:颜色(r:0.0,g:1.0,b:0.0,a:1.0))]
[]
[事件(ID:C7D9475B-773E-4272-84CC-56CAEAA73D0C,名称:“a”,开始:2021-01-26 05:17:30 +0000,结束:2021-01-26 05:17:30 +000,Event(id: 0BEA4225-2F63-4EEB-AF10-F3EF4C84D050,name : "b",开始: 2021-01-26 05:17:30 +0000,结束: 2021-01-26 05:17:30 +0000,color: Color (r: 0.0,g: 1.0,b: 0.0,a: 1.0))]
简单使用:
UserDefaults().set(try? PropertyListEncoder().encode(EventDataArray),forKey: "eventDataPersisted")
(当然,您可以随意命名密钥)。
此外,根据经验,变量名称通常跟在 camelCase 之后。
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