Ios SwiftUI预览版不支持';不显示(无错误)
我为TransactionListView.swift的PreviewProvider提供了以下代码:Ios SwiftUI预览版不支持';不显示(无错误),ios,swift,xcode,core-data,swiftui,Ios,Swift,Xcode,Core Data,Swiftui,我为TransactionListView.swift的PreviewProvider提供了以下代码: struct TransactionsListView_Previews: PreviewProvider { static var previews: some View { let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
struct TransactionsListView_Previews: PreviewProvider {
static var previews: some View {
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
let transaction = NPTransaction(context: context)
transaction.date = Date()
transaction.income = true
transaction.type = "morning"
transaction.value = 1200
transaction.notes = "notes"
return TransactionsListView(filter: true, startDate: Date()).environment(\.managedObjectContext, context)
}
}
预览未显示。存在生成成功的消息,并且没有错误消息,但画布为空。我做错了什么
另外,我使用的是CoreData,有一个名为NPTransaction的实体,它有5个属性:日期、收入、票据、类型、价值。因为Xcode没有给我任何错误,所以很难猜测。我需要在预览中添加addingTimeInterval to Date()。工作代码: 结构TransactionListView\u预览:PreviewProvider{
static var previews: some View {
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
let transaction = NPTransaction(context: context)
transaction.date = Date()
transaction.income = true
transaction.type = "morning"
transaction.value = 1200
transaction.notes = "notes"
return TransactionsListView(filter: true, startDate: Date().addingTimeInterval(-86400 * 30)).environment(\.managedObjectContext, context)
}
}
感谢@CranialDev在这里帮助了我:因为Xcode没有给我任何错误,所以很难猜测。我需要在预览中添加addingTimeInterval to Date()。工作代码: 结构TransactionListView\u预览:PreviewProvider{
static var previews: some View {
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
let transaction = NPTransaction(context: context)
transaction.date = Date()
transaction.income = true
transaction.type = "morning"
transaction.value = 1200
transaction.notes = "notes"
return TransactionsListView(filter: true, startDate: Date().addingTimeInterval(-86400 * 30)).environment(\.managedObjectContext, context)
}
}
感谢@CranialDev在这里帮助了我: