Swiftui 如何附加到结构数组并使更改持久化?
我希望能够将对象列表存储在单独的Swift文件中,并在页面中调用它们以显示它们。我成功地使用以下代码完成了此操作:Swiftui 如何附加到结构数组并使更改持久化?,swiftui,swift5,swiftui-list,Swiftui,Swift5,Swiftui List,我希望能够将对象列表存储在单独的Swift文件中,并在页面中调用它们以显示它们。我成功地使用以下代码完成了此操作: import Foundation import SwiftUI struct MatchInfo: Hashable, Codable { let theType: String let theWinner: String let theTime: String let id = UUID() } var matchInfo = [ Ma
import Foundation
import SwiftUI
struct MatchInfo: Hashable, Codable {
let theType: String
let theWinner: String
let theTime: String
let id = UUID()
}
var matchInfo = [
MatchInfo(theType: "Capitalism", theWinner: "Julia", theTime: "3/3/2021"),
MatchInfo(theType: "Socialism", theWinner: "Julia", theTime: "3/2/2021"),
MatchInfo(theType: "Authoritarianism", theWinner: "Luke", theTime: "3/1/2021")
]
其中,在另一个页面上播放比赛后,我将添加到列表中:
matchInfo.insert(MatchInfo(theType: typeSelection, theWinner: winnerName, theTime: "\(datetimeWithoutYear)" + "\(year)"), at: 0)
下面是另一页上的一些代码,我将其称为列表:
List {
ForEach(matchInfo, id: \.self) { matchData in
matchRow(matchData : matchData)
} .background(Color("invisble"))
.listRowBackground(Color("invisble"))
} .frame(height: 490)
但此代码不会通过应用程序重新启动保存。我以前从来没有通过重启来保存过东西,我一直在努力寻找一个简单到我能理解的答案。下次打开应用程序时,如何更新列表而不使其消失?好的,下面是一个关于如何保存到文档文件夹或从文档文件夹加载的示例 首先,确保对象MatchInfo符合此协议
import Foundation
protocol LocalFileStorable: Codable {
static var fileName: String { get }
}
extension LocalFileStorable {
static var localStorageURL: URL {
guard let documentDirectory = FileManager().urls(for: .documentDirectory, in: .userDomainMask).first else {
fatalError("Can NOT access file in Documents.")
}
return documentDirectory
.appendingPathComponent(self.fileName)
.appendingPathExtension("json")
}
}
extension LocalFileStorable {
static func loadFromFile() -> [Self] {
do {
let fileWrapper = try FileWrapper(url: Self.localStorageURL, options: .immediate)
guard let data = fileWrapper.regularFileContents else {
throw NSError()
}
return try JSONDecoder().decode([Self].self, from: data)
} catch _ {
print("Could not load \(Self.self) the model uses an empty collection (NO DATA).")
return []
}
}
}
extension LocalFileStorable {
static func saveToFile(_ collection: [Self]) {
do {
let data = try JSONEncoder().encode(collection)
let jsonFileWrapper = FileWrapper(regularFileWithContents: data)
try jsonFileWrapper.write(to: self.localStorageURL, options: .atomic, originalContentsURL: nil)
} catch _ {
print("Could not save \(Self.self)s to file named: \(self.localStorageURL.description)")
}
}
}
extension Array where Element: LocalFileStorable {
///Saves an array of LocalFileStorables to a file in Documents
func saveToFile() {
Element.saveToFile(self)
}
}
您的主要内容视图应该如下所示:(我修改了您的对象,使其更简单。)
谢谢,我想说的是,我可以成功地将它添加到我的列表中,并在其他地方显示出来,但我不知道如何通过应用程序重启来保存它。你有没有可能在这里告诉我该怎么做?我更新了答案并添加了一个代码示例。
import Foundation
protocol LocalFileStorable: Codable {
static var fileName: String { get }
}
extension LocalFileStorable {
static var localStorageURL: URL {
guard let documentDirectory = FileManager().urls(for: .documentDirectory, in: .userDomainMask).first else {
fatalError("Can NOT access file in Documents.")
}
return documentDirectory
.appendingPathComponent(self.fileName)
.appendingPathExtension("json")
}
}
extension LocalFileStorable {
static func loadFromFile() -> [Self] {
do {
let fileWrapper = try FileWrapper(url: Self.localStorageURL, options: .immediate)
guard let data = fileWrapper.regularFileContents else {
throw NSError()
}
return try JSONDecoder().decode([Self].self, from: data)
} catch _ {
print("Could not load \(Self.self) the model uses an empty collection (NO DATA).")
return []
}
}
}
extension LocalFileStorable {
static func saveToFile(_ collection: [Self]) {
do {
let data = try JSONEncoder().encode(collection)
let jsonFileWrapper = FileWrapper(regularFileWithContents: data)
try jsonFileWrapper.write(to: self.localStorageURL, options: .atomic, originalContentsURL: nil)
} catch _ {
print("Could not save \(Self.self)s to file named: \(self.localStorageURL.description)")
}
}
}
extension Array where Element: LocalFileStorable {
///Saves an array of LocalFileStorables to a file in Documents
func saveToFile() {
Element.saveToFile(self)
}
}
import SwiftUI
struct MatchInfo: Hashable, Codable, LocalFileStorable {
static var fileName: String {
return "MatchInfo"
}
let description: String
}
struct ContentView: View {
@State var matchInfos = [MatchInfo]()
var body: some View {
VStack {
Button("Add Match Info:") {
matchInfos.append(MatchInfo(description: "Nr." + matchInfos.count.description))
MatchInfo.saveToFile(matchInfos)
}
List(matchInfos, id: \.self) {
Text($0.description)
}
.onAppear(perform: {
matchInfos = MatchInfo.loadFromFile()
})
}
}
}