My problem is that i have (in SwiftUI) a ScrollView with an foreach inside. Know when the foreach loads all of my entries i want that the last entry is focused.
I did some google research, but i didn't find any answer.
ScrollView {
VStack {
ForEach (0..<self.entries.count) { index in
Group {
Text(self.entries[index].getName())
}
}
}
}
According to Apple's documentation on ScrollViewReader, it should wrap the scroll view, instead of being nested in.
Example from Apple docs:
@Namespace var topID
@Namespace var bottomID
var body: some View {
ScrollViewReader { proxy in
ScrollView {
Button("Scroll to Bottom") {
withAnimation {
proxy.scrollTo(bottomID)
}
}
.id(topID)
VStack(spacing: 0) {
ForEach(0..<100) { i in
color(fraction: Double(i) / 100)
.frame(height: 32)
}
}
Button("Top") {
withAnimation {
proxy.scrollTo(topID)
}
}
.id(bottomID)
}
}
}
func color(fraction: Double) -> Color {
Color(red: fraction, green: 1 - fraction, blue: 0.5)
}
This other article also shows how to use ScrollViewReader to wrap a List of elements, which can be also handy. Code example from the article:
ScrollViewReader { scrollView in
List {
ForEach(photos.indices) { index in
Image(photos[index])
.resizable()
.scaledToFill()
.cornerRadius(25)
.id(index)
}
}
.
.
.
}
For me, using value.scrollTo(entries.count - 1) does not work. Furthermore, using value.scrollTo(entries.last?.id) didn't work either until I used the
.id(...) view modifier (maybe because my entries do not conform to Identifiable).
Using ForEach, here is the code I'm working on:
ScrollViewReader { value in
ScrollView {
ForEach(state.messages, id: \.messageId) { message in
MessageView(message: message)
.id(message.messageId)
}
}
.onAppear {
value.scrollTo(state.messages.last?.messageId)
}
.onChange(of: state.messages.count) { _ in
value.scrollTo(state.messages.last?.messageId)
}
}
One important consideration when using onAppear is to use that modifier on the ScrollView/List and not in the ForEach. Doing so in the ForEach will cause it to trigger as elements on the list appear when manually scrolling through it.
I don't have enough reputation to post a comment yet, so here you go @Dam and @Evert
To scroll to the bottom whenever the number of entries in your ForEach changes you can also use the same method with a ScrollViewReader, as mentioned in the answer above, by adding the view modifier onChange like so:
struct ContentView: View {
let colors: [Color] = [.red, .blue, .green]
var entries: [Entry] = Array(repeating: Entry(), count: 10)
var body: some View {
ScrollView {
ScrollViewReader { value in
ForEach(0..<entries.count) { i in
Text(self.entries[i].getName())
.frame(width: 300, height: 200)
.background(colors[i % colors.count])
.padding(.all, 20)
}
.onChange(of: entries.count) { _ in
value.scrollTo(entries.count - 1)
}
}
}
}
}
There is a feature that comes with iOS 17: defaultScrollAnchor(_:)
ScrollView {
ForEach(0..<50) { i in
Text("Item \(i)")
.frame(maxWidth: .infinity)
.padding()
.background(.blue)
.clipShape(.rect(cornerRadius: 25))
}
}
.defaultScrollAnchor(.bottom)
ScrollViewReaderin iOS14 SwiftUI gains a new ability. To be able to scroll in a ScrollView up to a particular item with a given id. There is a new type called ScrollViewReader which works just like Geometry Reader.
The code below will scroll to the last item in your View.
So this is your struct for 'Entry' I guess:
struct Entry {
let id = UUID()
func getName() -> String {
return "Entry with id \(id.uuidString)"
}
}
And the main ContentView:
struct ContentView: View {
var entries: [Entry] = Array(repeating: Entry(), count: 10)
var body: some View {
ScrollView {
ScrollViewReader { value in
ForEach(entries, id: \.id) { entry in
Text(entry.getName())
.frame(width: 300, height: 200)
.padding(.all, 20)
}
.onAppear {
value.scrollTo(entries.last?.id, anchor: .center)
}
}
}
}
}
Try to run this in the new version of SwiftUI announced at WWDC20. I think it is a great enhancement.
All solutions provided here assume to have multiple child views, each with an id. But what if you have only one child, e.g. a multiline Text, that grows over time and you want to have this automatic scroll feature to the bottom?
You then simply can add an identifier (in my case "1"):
VStack {
ScrollViewReader { proxy in
ScrollView {
Text(historyText)
.id(1) // this is where to add an id
.multilineTextAlignment(.leading)
.padding()
}
.onChange(of: historyText) { _ in
proxy.scrollTo(1, anchor: .bottom)
}
}
}
Add a textview with empty string and an id at the bottom of scroll view then use scrollTo to scroll to this view whenever something changes. Here is the code
struct ContentView: View {
@Namespace var bottomID
@State var data : [Int] = []
init(){
var temp : [Int] = []
for i in 0...100 {
temp.append(i)
}
_data = .init(initialValue: temp)
}
var body: some View {
ScrollViewReader { value in
ScrollView {
ForEach(data, id: \.self) { i in
Text("\(i)")
}
// Empty text view with id
Text("").id(bottomID)
}
.onAppear{
withAnimation{
// scrolling to the text value present at bottom
value.scrollTo(bottomID)
}
}
}
}
}
I imagine we are all making chat apps here!
This is how I ended up doing, mostly inspired by answers here with a combo twist (after lots of trying)
struct ChatItemListView: View {
@StateObject var lesson: Lesson
var body: some View {
ScrollViewReader { scrollViewProxy in
List(lesson.safeChatItems) { chatItem in
ChatItemRowView(chatItem: chatItem).id(chatItem.id)
}
.onReceive(lesson.objectWillChange) { _ in
guard !lesson.chatItems.isEmpty else { return }
Task {
scrollViewProxy.scrollTo(
lesson.chatItems.last!.id,
anchor: .top
)
}
}
}
}
}
The two important details here are:
.id(chatItem.id)TaskWithout those, it did not work, even if my chatItem implements Identifiable protocol.
Here is the example, make sure to set the anchor then you can achieve your behavior easily
import SwiftUI
struct ContentView: View {
@Namespace private var topID
@Namespace private var bottomID
var body: some View {
VStack(spacing: 20) {
HStack {
Button("Scroll to Top") {
withAnimation {
proxy.scrollTo(topID, anchor: .top)
}
}
Button("Scroll to Bottom") {
withAnimation {
proxy.scrollTo(bottomID, anchor: .bottom)
}
}
}
ScrollViewReader { proxy in
ScrollView {
VStack(spacing: 20) {
Text("Top Text")
.id(topID)
.background(Color.yellow)
.padding()
ForEach(0..<30) { i in
Text("Dynamic Text \(i)")
.padding()
.background(i % 2 == 0 ? Color.blue : Color.green)
.foregroundColor(.white)
}
Text("Bottom Text")
.id(bottomID)
.background(Color.red)
.padding()
}
}
}
}
.padding()
}
}
@main
struct MyApp: App {
var body: some Scene {
WindowGroup {
ContentView()
}
}
}
