[英]Swift 5: ObservedObject Not updating
我創建了一個名為ActiveQuiz
的 ObservableObject 類,其中包含我想在多個視圖中共享的信息:
import Foundation
class ActiveQuiz: ObservableObject{
@Published var iterator = 0
@Published var questions = createQuiz()
}
在我顯示文本的一個視圖中,如果點擊它會增加迭代器,迭代器會隨着文本移動到問題數組中的下一個條目而更新文本:
import SwiftUI
struct Question: View {
@ObservedObject var activeQuiz = ActiveQuiz()
var body: some View {
Text(self.activeQuiz.questions[self.activeQuiz.iterator].countryInfo.capital)
.font(.title)
.onTapGesture(perform: {
// increase iterator by 1 unless it's at the end, then put back to 0
self.activeQuiz.iterator = self.activeQuiz.iterator + 1 == self.activeQuiz.questions.count ? 0 : self.activeQuiz.iterator + 1
} )
}
}
在另一個視圖中,我有一個計數,顯示迭代器的位置:
import SwiftUI
struct QuestionCounter: View {
@ObservedObject var activeQuiz = ActiveQuiz()
var body: some View {
Text(String(self.activeQuiz.iterator + 1) + "/" + String(self.activeQuiz.questions.count))
}
}
第一個視圖中的文本正在按預期更新,但第二個視圖中的迭代器保持在最初的 1/x。
問題:作為 Swift 新手,我不明白為什么ObservableObject
ActiveQuiz 的共享狀態沒有在“觀察”它的所有視圖中更新。 同樣是 swift 的新手,如果我沒有包含回答我不知道的問題所需的任何信息,我深表歉意。
目前尚不清楚,您如何一起使用這些視圖,例如,對於其他人來說,添加ContentView
可能會有所幫助。 如我所見,您使用了 2 個不同的ActiveQuiz
實例。 所以你的Question
結構有 1 個實例,你更新它的迭代器,而QuestionCounter
有它自己的實例,它不是從第一個更新的。 我認為解決方案應該是對兩個結構都使用@EnvironmentObject
,就像這樣(由於缺少代碼,我簡化了您的示例):
import SwiftUI
import Combine
class ActiveQuiz: ObservableObject {
@Published var iterator = 0
}
struct UsingEnvironmentObject: View {
@EnvironmentObject var activeQuiz: ActiveQuiz
var body: some View {
VStack {
Question() // it will take EnvironmentObject from parent
QuestionCounter() // this one will take the same EnvironmentObject from parent
}
}
}
// more representative solution
struct UsingEnvironmentObject: View {
@ObservedObject var activeQuiz = ActiveQuiz()
var body: some View {
VStack {
// here you see, that both structs use one instance
Question()
.environmentObject(activeQuiz)
QuestionCounter()
.environmentObject(activeQuiz)
}
}
}
struct Question: View {
@EnvironmentObject var activeQuiz: ActiveQuiz
var body: some View {
Text("some text from question")
.font(.title)
.onTapGesture(perform: {
// increase iterator by 1 unless it's at the end, then put back to 0
self.activeQuiz.iterator = self.activeQuiz.iterator + 1 == 10 ? 0 : self.activeQuiz.iterator + 1
} )
}
}
struct QuestionCounter: View {
@EnvironmentObject var activeQuiz: ActiveQuiz
var body: some View {
Text(String(self.activeQuiz.iterator + 1) + "/10")
}
}
struct UsingEnvironmentObject_Previews: PreviewProvider {
static var previews: some View {
UsingEnvironmentObject()
.environmentObject(ActiveQuiz())
}
}
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