我正在尝试重新创建与股票 iOS 日历应用程序中的事件列表匹配的视图。我有以下代码,它生成一个事件列表,每个事件按日期分为自己的部分:
var body: some View {
NavigationView {
List {
ForEach(userData.occurrences) { occurrence in
Section(header: Text("\(occurrence.start, formatter: Self.dateFormatter)")) {
NavigationLink(
destination: OccurrenceDetail(occurrence: occurrence)
.environmentObject(self.userData)
) {
OccurrenceRow(occurrence: occurrence)
}
}
}
}
.navigationBarTitle(Text("Events"))
}.onAppear(perform: populate)
}
这段代码的问题在于,如果同一日期有两个事件,它们会被分成具有相同标题的不同部分,而不是被组合到同一个部分中。
作为一个 Swift 新手,我的直觉是做这样的事情:
ForEach(userData.occurrences) { occurrence in
if occurrence.start != self.date {
Section(header: Text("\(occurrence.start, formatter: Self.dateFormatter)")) {
NavigationLink(
destination: OccurrenceDetail(occurrence: occurrence)
.environmentObject(self.userData)
) {
OccurrenceRow(occurrence: occurrence)
}
}
} else {
NavigationLink(
destination: OccurrenceDetail(occurrence: occurrence)
.environmentObject(self.userData)
) {
OccurrenceRow(occurrence: occurrence)
}
}
self.date = occurrence.start
但在 Swift 中,这给了我错误“无法推断复杂的闭包返回类型;添加显式类型以消除歧义”,因为我在 ForEach{} 中调用任意代码 (self.date =occurrence.start),这是不允许的.
实现这一点的正确方法是什么?有没有更动态的方法来执行它,还是我需要以某种方式抽象 ForEach{} 之外的代码?
编辑: Occurrence 对象如下所示:
struct Occurrence: Hashable, Codable, Identifiable {
var id: Int
var title: String
var description: String
var location: String
var start: Date
var end: String
var cancelled: Bool
var public_occurrence: Bool
var created: String
var last_updated: String
private enum CodingKeys : String, CodingKey {
case id, title, description, location, start, end, cancelled, public_occurrence = "public", created, last_updated
}
}
更新:以下代码为我提供了一个字典,其中包含由同一日期键入的事件数组:
let myDict = Dictionary( grouping: value ?? [], by: { occurrence -> String in
let dateFormatter = DateFormatter()
dateFormatter.dateStyle = .medium
dateFormatter.timeStyle = .none
return dateFormatter.string(from: occurrence.start)
})
self.userData.latestOccurrences = myDict
但是,如果我尝试在我的视图中使用它,如下所示:
ForEach(self.occurrencesByDate) { occurrenceSameDate in
// Section(header: Text("\(occurrenceSameDate[0].start, formatter: Self.dateFormatter)")) {
ForEach(occurrenceSameDate, id: occurrenceSameDate.id){ occurrence in
NavigationLink(
destination: OccurrenceDetail(occurrence: occurrence)
.environmentObject(self.userData)
) {
OccurrenceRow(occurrence: occurrence)
}
}
// }
}
(当我得到主要部分工作时,部分内容被注释掉了)
我收到此错误:无法将类型“_.Element”的值转换为预期的参数类型“发生”