How do I update the data in the tabview after the one-to-many coredata has been modified? - swift

Question

Purpose
I want to update the data in the tabview automatically when I return to the RootView after I rename the tag name in the tagManagemenView.
Current Status
When I do delete operation in the TagManagementView, the RootView is able to update automatically.
However, If the Tag name is modified, the RootView display will not be updated, but clicking into the ItemDetailsView is able to display the latest modified name. Only the display of the RootView is not updated.
Background and code
Item and Tag are created using coredata and have a one-to-many relationship, where one Item corresponds to multiple Tags
// RootView
struct RootView: View {
#State private var selection = 0
var body: some View {
NavigationView {
TabView(selection: $selection) {
ItemListView()
.tabItem {
Label ("Items",systemImage: "shippingbox")
}
.tag(0)
Settings()
.tabItem{
Label("Settings", systemImage: "gearshape")
}
.tag(1)
}
.navigationTitle(selection == 0 ? "Items" : "Settings")
}
.navigationViewStyle(.stack)
}
}
// ItemListView
struct ItemListView: View {
#FetchRequest var items: FetchedResults<Item>
#State private var itemDetailViewIsShow: Bool = false
#State private var selectedItem: Item? = nil
init() {
var predicate = NSPredicate(format: "TRUEPREDICATE"))
_items = FetchRequest(fetchRequest: Item.fetchRequest(predicate))
}
var body: some View {
ForEach(items) { item in
Button(action: {
self.selectedItem = item
self.itemDetailViewIsShow = true
}, label: {
ItemCellView(item: item)
})
}
if selectedItem != nil {
NavigationLink (
destination: ItemDetailView(item: selectedItem!, detailViewIsShow: $itemDetailViewIsShow),
isActive: $itemDetailViewIsShow
) {
EmptyView()
}
.isDetailLink(false)
}
}
}
// TagManagementView
struct TagManagementView: View {
#Environment(\.managedObjectContext) var context
#FetchRequest(entity: Tag.entity(), sortDescriptors: []) var allTags: FetchedResults<Tag>
#State var isShowDeleteAlert = false
#State var showModel = false
#State var selected: Tag?
var body: some View {
ZStack {
List {
ForEach(allTags) { tag in
TagCellView(tag: tag)
.swipeActions(edge: .trailing, allowsFullSwipe: false) {
Button(role: .destructive, action: {
isShowDeleteAlert = true
selected = tag
}, label: {
Label("Delete", systemImage: "trash")
.foregroundColor(.white)
})
Button(action: {
showModel = true
selected = tag
}, label: {
Label("Edit", systemImage: "square.and.pencil")
.foregroundColor(.white)
})
}
}
.confirmationDialog("Delete confirm", isPresented: self.$isShowDeleteAlert, titleVisibility: .visible) {
Button("Delete", role: .destructive) {
if self.selected != nil {
self.selected!.delete(context: context)
}
}
Button(role: .cancel, action: {
isShowDeleteAlert = false
}, label: {
Text("Cancel")
.font(.system(size: 17, weight: .medium))
})
}
}
if self.showModel {
// background...
Color("mask").edgesIgnoringSafeArea(.all)
TagEditorModal(selected: self.$selected, isShowing: self.$showModel)
}
}
}
}
// TagEditorModal
struct TagEditorModal: View {
#Environment(\.managedObjectContext) var context
#State var tagName: String = ""
#Binding var isShowing: Bool
#Binding var selector: Tag?
init (selected: Binding<Tag?>, isShowing: Binding<Bool>) {
_isShowing = isShowing
_selector = selected
_tagName = .init(wrappedValue: selected.wrappedValue!.name)
}
var body: some View {
VStack{
TextField("Tag name", text: self.$tagName)
HStack {
Button(action: {
self.isShowing = false
}) {
Text("Cancel")
}
Button(action: {
self.selector!.update(name: self.tagName, context: context)
self.isShowing = false
}, label: {
Text("Submit")
})
}
}
}
}
// update tagName func
extension Tag {
func update(name: String, context: NSManagedObjectContext) {
self.name = name
self.updatedAt = Date()
self.objectWillChange.send()
try? context.save()
}
}
// ItemCellView
struct ItemCellView: View {
#Environment(\.managedObjectContext) var context
#ObservedObject var item: Item
var body: some View {
VStack {
Text(item.name)
TagListView(tags: .constant(item.tags))
}
}
}
// tagListView
struct TagListView: View {
#Binding var tags: [Tag]
#State private var totalHeight = CGFloat.zero
var body: some View {
VStack {
GeometryReader { geo in
VStack(alignment: .leading,spacing: 10) {
ForEach (getRows(screenWidth: geo.size.width), id: \.self) {rows in
HStack(spacing: 4) {
ForEach (rows) { tag in
Text(tag.name)
.font(.system(size: 10))
.fontWeight(.medium)
.lineLimit(1)
.cornerRadius(40)
}
}
}
}
.frame(width: geo.size.width, alignment: .leading)
.background(viewHeightReader($totalHeight))
}
}
.frame(height: totalHeight)
}
private func viewHeightReader(_ binding: Binding<CGFloat>) -> some View {
return GeometryReader { geo -> Color in
let rect = geo.frame(in: .local)
DispatchQueue.main.async {
binding.wrappedValue = rect.size.height
}
return .clear
}
}
func getRows(screenWidth: CGFloat) -> [[Tag]] {
var rows: [[Tag]] = []
var currentRow: [Tag] = []
var totalWidth: CGFloat = 0
self.tags.forEach{ tag in
totalWidth += (tag.size + 24)
if totalWidth > (screenWidth) {
totalWidth = (!currentRow.isEmpty || rows.isEmpty ? (tag.size + 24) : 0)
rows.append(currentRow)
currentRow.removeAll()
currentRow.append(tag)
} else {
currentRow.append(tag)
}
}
if !currentRow.isEmpty {
rows.append(currentRow)
currentRow.removeAll()
}
return rows
}
}

Answer 1

I added a TagCellView and then used an #ObservedObject for the tag
struct TagChipsView: View {
#ObservedObject var tag: Tag
let verticalPadding: CGFloat = 2.0
let horizontalPadding: CGFloat = 8.0
var body: some View {
Text(tag.name)
}
}