SwiftUI: How to select multi items(image) with ForEach? - foreach

Question

I'm working on my project with the feature of select multiple blocks of thumbnails. Only selected thumbnail(s)/image will be highlighted.
For the ChildView, The binding activeBlock should be turned true/false if a use taps on the image.
However, when I select a thumbnail, all thumbnails will be highlighted.I have come up with some ideas like
#State var selectedBlocks:[Bool]
// which should contain wether or not a certain block is selected.
But I don't know how to implement it.
Here are my codes:
ChildView
#Binding var activeBlock:Bool
var thumbnail: String
var body: some View {
VStack {
ZStack {
Image(thumbnail)
.resizable()
.frame(width: 80, height: 80)
.background(Color.black)
.cornerRadius(10)
if activeBlock {
RoundedRectangle(cornerRadius: 10)
.stroke(style: StrokeStyle(lineWidth: 2))
.frame(width: 80, height: 80)
.foregroundColor(Color("orange"))
}
}
}
BlockBView
struct VideoData: Identifiable{
var id = UUID()
var thumbnails: String
}
struct BlockView: View {
var videos:[VideoData] = [
VideoData(thumbnails: "test"), VideoData(thumbnails: "test2"), VideoData(thumbnails: "test1")
]
#State var activeBlock = false
var body: some View {
ScrollView(.horizontal){
HStack {
ForEach(0..<videos.count) { _ in
Button(action: {
self.activeBlock.toggle()
}, label: {
ChildView(activeBlock: $activeBlock, thumbnail: "test")
})
}
}
}
}
Thank you for your help!

Answer 1

Here is a demo of possible approach - we initialize array of Bool by videos count and pass activated flag by index into child view.
Tested with Xcode 12.1 / iOS 14.1 (with some replicated code)
struct BlockView: View {
var videos:[VideoData] = [
VideoData(thumbnails: "flag-1"), VideoData(thumbnails: "flag-2"), VideoData(thumbnails: "flag-3")
]
#State private var activeBlocks: [Bool] // << declare
init() {
// initialize state with needed count of bools
self._activeBlocks = State(initialValue: Array(repeating: false, count: videos.count))
}
var body: some View {
ScrollView(.horizontal){
HStack {
ForEach(videos.indices, id: \.self) { i in
Button(action: {
self.activeBlocks[i].toggle() // << here !!
}, label: {
ChildView(activeBlock: activeBlocks[i], // << here !!
thumbnail: videos[i].thumbnails)
})
}
}
}
}
}
struct ChildView: View {
var activeBlock:Bool // << value, no binding needed
var thumbnail: String
var body: some View {
VStack {
ZStack {
Image(thumbnail)
.resizable()
.frame(width: 80, height: 80)
.background(Color.black)
.cornerRadius(10)
if activeBlock {
RoundedRectangle(cornerRadius: 10)
.stroke(style: StrokeStyle(lineWidth: 2))
.frame(width: 80, height: 80)
.foregroundColor(Color.orange)
}
}
}
}
}

Answer 2

Final result
Build your element and it's model first. I'm using MVVM,
class RowModel : ObservableObject, Identifiable {
#Published var isSelected = false
#Published var thumnailIcon: String
#Published var name: String
var id : String
var cancellables = Set<AnyCancellable>()
init(id: String, name: String, icon: String) {
self.id = id
self.name = name
self.thumnailIcon = icon
}
}
//Equivalent to your BlockView
struct Row : View {
#ObservedObject var model: RowModel
var body: some View {
GroupBox(label:
Label(model.name, systemImage: model.thumnailIcon)
.foregroundColor(model.isSelected ? Color.orange : .gray)
) {
HStack {
Capsule()
.fill(model.isSelected ? Color.orange : .gray)
.onTapGesture {
model.isSelected = !model.isSelected
}
//Two way binding
Toggle("", isOn: $model.isSelected)
}
}.animation(.spring())
}
}
Prepare data and handle action in your parent view
struct ContentView: View {
private let layout = [GridItem(.flexible()),GridItem(.flexible())]
#ObservedObject var model = ContentModel()
var body: some View {
VStack {
ScrollView {
LazyVGrid(columns: layout) {
ForEach(model.rowModels) { model in
Row(model: model)
}
}
}
if model.selected.count > 0 {
HStack {
Text(model.selected.joined(separator: ", "))
Spacer()
Button(action: {
model.clearSelection()
}, label: {
Text("Clear")
})
}
}
}
.padding()
.onAppear(perform: prepare)
}
func prepare() {
model.prepare()
}
}
class ContentModel: ObservableObject {
#Published var rowModels = [RowModel]()
//I'm handling by ID for futher use
//But you can convert to your Array of Boolean
#Published var selected = Set<String>()
func prepare() {
for i in 0..<20 {
let row = RowModel(id: "\(i)", name: "Block \(i)", icon: "heart.fill")
row.$isSelected
.removeDuplicates()
.receive(on: RunLoop.main)
.sink(receiveValue: { [weak self] selected in
guard let `self` = self else { return }
print(selected)
if selected {
self.selected.insert(row.name)
}else{
self.selected.remove(row.name)
}
}).store(in: &row.cancellables)
rowModels.append(row)
}
}
func clearSelection() {
for r in rowModels {
r.isSelected = false
}
}
}
Don't forget to import Combine framework.