TabView 上的元素删除后不消失

Question

我有这个 class:

class PageViewModel:ObservableObject {
  @Published var cars = [Car]()   
  
  func delete(_ car:Car) {
    cars = cars.filter { [=10=] != car }
  }
  
}

然后我将这个 class 传递给一个名为 PageView 的视图，就像这样

@ObservedObject private var pageViewModel = PageViewModel()

var body: some View {
  PageView(pageViewModel)

这是PageView:

struct PageView: View {
  @ObservedObject private var pageViewModel:PageViewModel
  
  init(_ pageViewModel:PageViewModel) {
    self.pageViewModel = pageViewModel
  }
  
  var body: some View {
    TabView() {
      ForEach(pageViewModel.cars) { car in
        TopPanel(car, pageViewModel)
          .frame(maxWidth: .infinity)
          .padding([.leading, .trailing], 10)
          .padding(.bottom,60)
        
      }
    }
    .frame(height: 220)
    .tabViewStyle(PageTabViewStyle())
    .indexViewStyle(PageIndexViewStyle(backgroundDisplayMode: .always))
  }
}

注意：Car是一个NSManagedObject，所以默认是@ObservableObject。在这里

汽车+CoreDataClass.swift

import Foundation
import CoreData

@objc(Car)
public class Car: NSManagedObject {
}

汽车+CoreDataProperties

extension Car : Encodable {
  
  @nonobjc public dynamic class func fetchRequest() -> NSFetchRequest<Car> {
    return NSFetchRequest<Car>(entityName: "Car")
  }
  
  @NSManaged public var model: String?
  @NSManaged public var brand: String?

这是 TopPanel 问题的根源。

struct TopPanel: View {
@ObservedObject private var car:Car
@ObservedObject private var pageViewModel:PageViewModel
  
init(_ car:Car,
     _ pageViewModel:PageViewModel?) {
  self.car = car
  self.pageViewModel = model
}

var body: some View {
  Button(action: {
    pageViewModel.delete(car)
}, label: {
  Text("delete me")
})

请记住，TabView 显示的是 TopPanel 的页面，而此 TopPanel 有一个按钮，允许用户从 TabView 中删除自己。

问题是，当我在给定元素上按删除键时，它继续显示在 TabView 上，但 TabView 上的一个点被删除了。如果在那之后我尝试删除第二个，我会收到此消息：

*** Assertion failure in -[_TtC7SwiftUIP33_8825076C2763A50452A210CBE1FA4AF020PagingCollectionView _endItemAnimationsWithInvalidationContext:tentativelyForReordering:animator:collectionViewAnimator:], UICollectionView.m:6982

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'attempt to delete and reload the same index path (<NSIndexPath: 0xacce8bbd6a5ce2d8> {length = 2, path = 0 - 1})'

我该如何解决？

Answer 1

难以置信，我发现了如何解决这个问题，完全是偶然的。

只需添加

    .id(pageViewModel.cars.count)

到 TabView。这将强制它在删除项目时更新。

TabView 上的元素删除后不消失

Element on TabView does not disappear after being deleted

tabview

swift

swiftui