我是SwiftUI的新手，无法绕过这个错误。我试图在同一初始值设定项中的另一个数组中使用两个@State变量(isGlobal和dataType(。
我不断得到错误："无法在属性初始值设定项中使用实例成员"dateType"；属性初始值设定项在"self"可用之前运行；和"无法在属性初始值设定项中使用实例成员"isGlobal"；属性初始值设定项在"self"可用之前运行；
这是视图开头的代码：
struct Home : View {
@State var dateType : Int
@State var isGlobal = true
@State var dailyVax = [
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 6))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 6))", show: true),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 5))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 5))", show: false),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 4))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 4))", show: false),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 3))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 3))", show: false),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 2))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 2))", show: false),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 1))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 1))", show: false),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 0))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 0))", show: false),
]
var body: some View { ...
这是[每日疫苗接种]结构：
struct DailyVaccinations : Identifiable {
var id = UUID().uuidString
var day : String
var value : String
var show : Bool
}
这是实际使用"；dailyVax"；阵列：
ForEach(dailyVax.indices,id: .self){i in
GraphView(data: dailyVax[i], allData: dailyVax)
.onTapGesture {
withAnimation{
for index in 0..<dailyVax.count{
dailyVax[index].show = false
}
dailyVax[i].show.toggle()
}
}
if dailyVax[i].value != dailyVax.last!.value {
Spacer(minLength: 0)
}
} ...
如果有人能帮我解决这个问题，我将不胜感激！谢谢
您收到此错误消息是因为您正试图访问初始化器内部的isGlobal和dateType。
当所有的值都还没有定义时，你不能这样做，因此；在自身可用之前"；在错误消息中。
要解决此问题，请编写一个自定义初始值设定项：
init(dateType: Int, isGlobal: Bool = true) {
self.dateType = dateType
self.isGlobal = isGlobal
self.dailyVax = [
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 6))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 6))", show: true),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 5))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 5))", show: false),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 4))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 4))", show: false),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 3))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 3))", show: false),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 2))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 2))", show: false),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 1))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 1))", show: false),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 0))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 0))", show: false)
]
// Note that all values are being given a value in the initializer (dateType, isGlobal, and dailyVax)
}
通过这样做，SwiftUI知道在更改和/或使用初始化器中提供的任何其他值之前，所有值都已初始化。我对SwiftUI也很陌生，但这是我对它的理解。有关初始化程序如何工作以及它们可以做什么的更多信息，我建议在谷歌上搜索更多关于这个主题的信息，和/或访问Swift官方文档：
https://docs.swift.org/swift-book/LanguageGuide/Initialization.html
这就是你的代码最终应该是什么样子的：
struct Home : View {
@State var dateType: Int
@State var isGlobal: Bool
@State var dailyVax: [DailyVaccinations]
init(dateType: Int, isGlobal: Bool = true) {
self.dateType = dateType
self.isGlobal = isGlobal
self.dailyVax = [
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 6))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 6))", show: true),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 5))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 5))", show: false),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 4))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 4))", show: false),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 3))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 3))", show: false),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 2))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 2))", show: false),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 1))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 1))", show: false),
DailyVaccinations(day: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: false, dayCt: 0))", value: "(showData(tabType: isGlobal, date: dateType, dataType: 4, change: true, dayCt: 0))", show: false)
]
}
var body: some View {
...
}
}