[英]SwiftUI: Toggle for individual items of ForEach
使用ForEach
,我想為每一行創建單獨的切換。 現在, @State
綁定同時切換所有項目,我不知道如何將它們分開。
在下面的代碼中,我放了一個硬編碼的數組,但它確實來自一個不斷變化的.json文件。 因此,我需要ForEach
和綁定是動態的。
這篇關於隱藏List
項的文章和這篇關於List
行問題的文章很有幫助,但我無法使綁定適用於我的項目。 我在第 2 天試圖弄清楚這一點,我在網上找到的內容都沒有解決這個具體問題。
下面是我的代碼的一個小例子,它重現了我的挑戰。 數組中的動態數據來自.json 文件。
import SwiftUI
struct GreekWords: Codable, Hashable {
var greekWordArray = ["Alpha", "Beta", "Gamma", "Delta", "Epsilon", "Zeta"]
// The array data comes from a dynamic .json file
}
struct ContentView: View {
var greekWords: GreekWords
@State private var wordToggle = false
var body: some View {
VStack(spacing: 0) {
ForEach(greekWords.greekWordArray, id: \.self) { word in
Toggle(word, isOn: $wordToggle)
}
}
.padding(.horizontal)
}
}
我希望這是一個簡單的解決方案,所以我提前感謝您的幫助。 另外,如果您能指出我更好地學習 SwiftUI 的任何方向,我將不勝感激。 我已經在 HackingWithSwift 上嘗試了所有 Apple 教程和書籍以及 SwiftUI 的 100 天。
干杯!
在您的示例代碼中,所有切換都引用同一個變量。 因此,當然所有切換都將始終顯示相同的 state。
在您提供的鏈接中的示例實現中,它不僅僅是一個字符串數組,它是一個對象數組,還包含一個 bool 變量來通過切換控制該特定項目。
更新(2):
也許以下方法更符合您的預期。 抱歉,昨晚沒想到。 但請記住,切換 state 的 var 僅在該視圖中可用,您可以在該視圖中顯示狀態,但不能真正使用它。 如果您想(重新)使用該信息,我寧願選擇昨晚的替代方案(見下文)。
//
// GreekWordTest.swift
// GreekWordTest
//
// Created by Sebastian on 15.08.22.
//
import SwiftUI
struct GreekWords: Codable, Hashable {
var greekWordArray = ["Alpha", "Beta", "Gamma", "Delta", "Epsilon", "Zeta"]
// The array data comes from a dynamic .json file
}
struct ContentView: View {
var greekWords: GreekWords
var body: some View {
VStack(spacing: 0) {
ForEach(greekWords.greekWordArray, id: \.self) { word in
GreekWordToggleView(greekWord: word)
.padding()
}
}
.padding(.horizontal)
}
}
struct GreekWordToggleView: View {
var greekWord: String
@State private var wordToggle = false
var body: some View {
VStack(spacing: 0) {
Toggle(greekWord, isOn: $wordToggle)
}
.padding(.horizontal)
}
}
這里是截圖:
選擇:
昨晚的接近
//
// GreekWordTest.swift
// GreekWordTest
//
// Created by Sebastian on 14.08.22.
//
import SwiftUI
struct ContentView: View {
@StateObject var greekWordsViewModel = GreekWordsViewModel()
var body: some View {
VStack() {
GreekWordView(greekWordsViewModel: greekWordsViewModel)
}
// For this test I am fetching the data once in the beginning when ContentView apears the first time, later I also added a button to fetch it again, it'll overwrite the existing data. You can also add a logic just to update it, that is up to you and your needs.
.onAppear(){
greekWordsViewModel.fetchData()
}
}
}
struct GreekWordView: View {
@ObservedObject var greekWordsViewModel: GreekWordsViewModel
var body: some View {
VStack(){
ForEach(greekWordsViewModel.greekWordArray.indices, id: \.self){ id in
Toggle(greekWordsViewModel.greekWordArray[id].name, isOn: $greekWordsViewModel.greekWordArray[id].isOn)
.padding()
}
// Here is the extra button to (re-)fetch the data from the json.
Button(action: {
greekWordsViewModel.fetchData()
}) {
Text("Fetch Data")
}
.padding()
}
}
}
struct GreekWord: Identifiable, Hashable {
var id: String = UUID().uuidString
var name: String
var isOn: Bool
}
class GreekWordsViewModel: ObservableObject {
@Published var greekWordArray: [GreekWord] = []
func fetchData(){
// As mentioned above, in his example I empty the array on each new loading event. You can also implement a logic to just update the data.
greekWordArray = []
let greekWords: [String] = load("greekWordsData.json")
for greekWord in greekWords {
greekWordArray.append(GreekWord(name: greekWord, isOn: false))
}
}
}
為了解碼 json,我使用了以下內容:
//
// ModelData.swift
// SwiftTest
//
// Created by Sebastian Fox on 14.08.22.
//
import Foundation
// This function is used to decode a file with a json. I guess you already created something that is decoding a json according to your need, of course you can still use it.
func load<T: Decodable>(_ filename: String) -> T {
let data: Data
guard let file = Bundle.main.url(forResource: filename, withExtension: nil)
else {
fatalError("Couldn't find \(filename) in main bundle.")
}
do {
data = try Data(contentsOf: file)
} catch {
fatalError("Couldn't load \(filename) from main bundle:\n\(error)")
}
do {
let decoder = JSONDecoder()
return try decoder.decode(T.self, from: data)
} catch {
fatalError("Couldn't parse \(filename) as \(T.self):\n\(error)")
}
}
最后為了測試,我使用了一個非常簡單的 greekWordsData.json 文件,它只包含:
["Alpha", "Beta", "Delta", "Gamma", "Epsilon", "Zeta"]
這是一個屏幕截圖:
最好的,塞巴斯蒂安
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