SwiftUI: Alternatives to using ListView? - swiftui

I want to have a scrollable list that when each row is tapped, it takes you to a different view. Inside each row, I want to have a heart button that when tapped overrides the navigation behavior and just toggles a heart fill/unfill.
As an alternative to do this, would it make sense to use a ScrollView inside a NavigationView and then have each list item be a VStack?
Pseudocode hierarchy:
NavigationView {
ScrollView {
VStack {
// Button
}
}
}
Is there a better way ( or more preferred way) to accomplish this?

Use LazyVStack
let items = ["A","B"]
var body: some View {
ScrollView {
LazyVStack(spacing: 10) {
ForEach(items, id: \.self) { item in
Text(item)
}
}
}
}

Related

How to trigger a NavigationLink programmatically in a LazyVGrid

I have a LazyVGrid inside a NavigationView.
NavigationView {
ScrollView {
LazyVGrid(columns: columns) {
ForEach(items) { item in
NavigationLink(tag: item, selection: $displayedItem) {
DetailView(item)
} label: {
GridItemView(item)
}
}
}
}
}
The referenced variables are defined as follows on the view:
#State var displayedItem: Item?
let columns: [GridItem] = Array(repeating: .init(.flexible()), count: 2)
Now I want to show the detail view for a specific item. I do this by simply assigning this item to the displayedItem property:
func showDetailView(for item: Item) {
displayedItem = item
}
This works great when the respective item is visible on the LazyVGrid at the moment when I call this function. However, when the item is not visible, I first need to scroll to the item for the NavigationLink to fire. I know why this is happening (because the items are loaded lazily, it's a lazy grid after all), but I don't know how to make the LazyVGrid load the specific item when I need it.
What I've tried:
I have also tried to programmatically scroll to the target item by wrapping the entire ScrollView inside a ScrollViewReader and appending the following modifier:
.onChange(of: displayedItem) { item in
if let item = item {
scrollProxy.scrollTo(item.id)
}
}
Unfortunately, this has the same problem: Scrolling to a given item doesn't work until the item is loaded.
Question:
Is there any way to make this work, i.e. to trigger a NavigationLink for an item that is not currently visible in the LazyVGrid? (It's important for me as I need this functionality to deep-link to a specific item's DetailView.)
An possible approach can be like in this topic - use one link somewhere in background of ScrollView and activate it by tapGesture/button from user or assigning corresponding value programmatically.
Tested with Xcode 13.4 / iOS 15.5
Main part:
ScrollView {
LazyVGrid(columns: columns) {
ForEach(items) { item in
RoundedRectangle(cornerRadius: 16).fill(.yellow)
.frame(maxWidth: .infinity).aspectRatio(1, contentMode: .fit)
.overlay(Text("Item \(item.value)"))
.onTapGesture {
selectedItem = item
}
}
}
}
.padding(.horizontal)
.background(
NavigationLink(destination: DetailView(item: selectedItem), isActive: isActive) {
EmptyView()
}
)
.toolbar {
Button("Random") { selectedItem = items.randomElement() }
}
Test module on GitHub

SwiftUI - Animation not working for a subview inside parent scrollView

I have horizontal menu scrollView inside Parent vertical scrollView. When I select menu, it refresh it refreshes listView. But to fix parent scrollView content size, I need to refresh entire View (scrollView) by assigning menuItem selected id to parent scrollView.
Everything works as expected but as I have assigned menuItem id to parent scrollView to fix content size/height issue, animation for scrolling selected menu doesn't work.
Is there any way I can achieve this animation?
struct SampleScrollView: View {
// Parent scroll view to fit multiple sub-views
ScrollView(.vetical, showsIndicators: false) {
Vstack {
HStack {
ScrollView(.horizontal, showsIndicators: false) {
ScrollViewReader { proxy in
HStack {
ForEach(Menus, id: \.menuItem) { menu in
Button(action: {
// This animation is not working as parent scrollView gets assigned with this selected menuItem id on menu click which helps Parent ScrollView to get refreshed so parent scrollview content size get's refreshed based on content height of result list view.
withAnimation {
proxy.scrollTo(menuItem, anchor: .leading)
}
LoadList()
}) {
Text("Option \(menuItem)")
}
}
}
}
}
}
VStack {
ScrollView(.vertical, showsIndicators: false) {
LazyVStack {
ForEach(resultArray, id: \.self) { item in
Text(item.title)
}
}
}
}
// Some other views here
VStack { }
}.id(menuItem) // Parent ScrollView Id get's updated every time when menu button selected
}
}

LazyVGrid onTapGesture navigate to next screen swiftUI

I am quite new to swiftUI. I have created a grid view on tapping on which I want to go to next screen. But somehow I am not able to manage to push to next screen. I am doing like this:
var body: some View {
NavigationView {
ScrollView {
LazyVGrid(columns: gridItems, spacing: 16) {
ForEach(viewModel.pokemon) { pokemon in
PokemonCell(pokemon: pokemon, viewModel: viewModel)
.onTapGesture {
NavigationLink(destination: PokemonDetailView(pokemon: pokemon)) {
Text(pokemon.name)
}
}
}
}
}
.navigationTitle("Pokedex")
}
}
Upon doing like this, I am getting a warning stating
Result of 'NavigationLink<Label, Destination>' initializer is unused
Can someone please guide me, how to do this?
.onTapGesture adds an action to perform when the view recognizes a tap gesture. In your case you don't need to use .onTapGesture. If you want to go to another view when cell is tapped you need to write NavigationLink as below.
NavigationLink(destination: PokemonDetailView(pokemon: pokemon)) {
PokemonCell(pokemon: pokemon, viewModel: viewModel)
}
If you want to use .onTapGesture, another approach is creating #State for your tapped cell's pokemon and using NavigationLink's isActive binding. So when user tap the cell it will change the #State and toggle the isActive in .onTapGesture. You may need to add another Stack (ZStack etc.) for this.
NavigationView {
ZStack {
NavigationLink("", destination: PokemonDetailView(pokemon: pokemon), isActive: $isNavigationActive).hidden()
ScrollView {
// ...

SwiftUI List is not showing any items

I want to use NavigationView together with the ScrollView, but I am not seeing List items.
struct ContentView: View {
var body: some View {
NavigationView {
ScrollView{
VStack {
Text("Some stuff 1")
List{
Text("one").padding()
Text("two").padding()
Text("three").padding()
}
Text("Some stuff 2")
}
}
}
}
}
All I see is the text. If I remove ScrollView I see it all, but the text is being pushed to the very bottom. I simply want to be able to add List and Views in a nice scrollable page.
The ScrollView expects dimension from content, but List expects dimension from container - as you see there is conflict, so size for list is undefined, and a result rendering engine just drop it to avoid disambiguty.
The solution is to define some size to List, depending of your needs, so ScrollView would now how to lay out it, so scroll view could scroll entire content and list could scroll internal content.
Eg.
struct ContentView: View {
#Environment(\.defaultMinListRowHeight) var minRowHeight
var body: some View {
NavigationView {
ScrollView{
VStack {
Text("Some stuff 1")
List {
Text("one").padding()
Text("two").padding()
Text("three").padding()
}.frame(minHeight: minRowHeight * 3).border(Color.red)
Text("Some stuff 2")
}
}
}
}
}
Just wanted to throw out an answer that fixed what I was seeing very similar to the original problem - I had put a Label() item ahead of my List{ ... } section, and when I deleted that Label() { } I was able to see my List content again. Possibly List is buggy with other items surrounding it (Xcode 13 Beta 5).

SwiftUI List - How to scroll to item

I have list with items. How can i scroll to list 12. I can use geometry reader to calculate offset. But how to scroll to this offset?
List {
ForEach(0..<12) { index in
Text("...")
}
}
Form Xcode 12, You can turn in to a ScrollView and then you can do it by .scrollTo(id):
var body: some View {
ScrollViewReader { scrollProxy in
ScrollView {
ForEach((1...100), id: \.self) { Text("\($0)") }
}
Button("Go!") {
withAnimation { scrollProxy.scrollTo(50) }
}
}
}
Note that ScrollViewReader should support all scrollable content, but now it only supports ScrollView