I'd like to present a sheet descending from the toolbar's bottom edge in a SwiftUI MacOS app. How can I specify that attachment point?
The methods below present a sheet at the view's center.
I had thought attachment was implied in .beginSheet(). Answers I see discussing this use Storyboards, but I'd like to stick to code.
struct SomeView: View {
func presentsSheetAtWindowCenter() {
guard let mainWindow = NSApp.mainWindow else { return }
let host = NSHostingController(rootView: someView)
let sheetWindow = NSWindow(contentViewController: host)
mainWindow.beginSheet(sheetWindow) { (response) in
//
}
}
func presentsSheetAtWindowCenterToo() {
guard let mainCVC = NSApp.mainWindow?.contentViewController else { return }
let host = NSHostingController(rootView: someView)
mainCVC.presentAsSheet(host)
}
}
Related
I want to have a Bool property, that represents that option key is pressed #Publised var isOptionPressed = false. I would use it for changing SwiftUI View.
For that, I think, that I should use Combine to observe for key pressure.
I tried to find an NSNotification for that event, but it seems to me that there are no any NSNotification, that could be useful to me.
Since you are working through SwiftUI, I would recommend taking things just a step beyond watching a Publisher and put the state of the modifier flags in the SwiftUI Environment. It is my opinion that it will fit in nicely with SwiftUI's declarative syntax.
I had another implementation of this, but took the solution you found and adapted it.
import Cocoa
import SwiftUI
import Combine
struct KeyModifierFlags: EnvironmentKey {
static let defaultValue = NSEvent.ModifierFlags([])
}
extension EnvironmentValues {
var keyModifierFlags: NSEvent.ModifierFlags {
get { self[KeyModifierFlags.self] }
set { self[KeyModifierFlags.self] = newValue }
}
}
struct ModifierFlagEnvironment<Content>: View where Content:View {
#StateObject var flagState = ModifierFlags()
let content: Content;
init(#ViewBuilder content: () -> Content) {
self.content = content();
}
var body: some View {
content
.environment(\.keyModifierFlags, flagState.modifierFlags)
}
}
final class ModifierFlags: ObservableObject {
#Published var modifierFlags = NSEvent.ModifierFlags([])
init() {
NSEvent.addLocalMonitorForEvents(matching: .flagsChanged) { [weak self] event in
self?.modifierFlags = event.modifierFlags
return event;
}
}
}
Note that my event closure is returning the event passed in. If you return nil you will prevent the event from going farther and someone else in the system may want to see it.
The struct KeyModifierFlags sets up a new item to be added to the view Environment. The extension to EnvironmentValues lets us store and
retrieve the current flags from the environment.
Finally there is the ModifierFlagEnvironment view. It has no content of its own - that is passed to the initializer in an #ViewBuilder function. What it does do is provide the StateObject that contains the state monitor, and it passes it's current value for the modifier flags into the Environment of the content.
To use the ModifierFlagEnvironment you wrap a top-level view in your hierarchy with it. In a simple Cocoa app built from the default Xcode template, I changed the application SwiftUI content to be:
struct KeyWatcherApp: App {
var body: some Scene {
WindowGroup {
ModifierFlagEnvironment {
ContentView()
}
}
}
}
So all of the views in the application could watch the flags.
Then to make use of it you could do:
struct ContentView: View {
#Environment(\.keyModifierFlags) var modifierFlags: NSEvent.ModifierFlags
var body: some View {
VStack {
Image(systemName: "globe")
.imageScale(.large)
.foregroundColor(.accentColor)
if(modifierFlags.contains(.option)) {
Text("Option is pressed")
} else {
Text("Option is up")
}
}
.padding()
}
}
Here the content view watches the environment for the flags and the view makes decisions on what to show using the current modifiers.
Ok, I found easy solution for my problem:
class KeyPressedController: ObservableObject {
#Published var isOptionPressed = false
init() {
NSEvent.addLocalMonitorForEvents(matching: .flagsChanged) { [weak self] event -> NSEvent? in
if event.modifierFlags.contains(.option) {
self?.isOptionPressed = true
} else {
self?.isOptionPressed = false
}
return nil
}
}
}
as per the documentation, it should be pretty straightforward. example for a List: https://developer.apple.com/documentation/swiftui/list/ondrop(of:istargeted:perform:)-75hvy#
the UTType should be the parameter restricting what a SwiftUI object can receive. in my case i want to accept only Apps. the UTType is .applicationBundle: https://developer.apple.com/documentation/uniformtypeidentifiers/uttype/3551459-applicationbundle
but it doesn't work. the SwiftUI object never changes status and never accepts the drop. the closure is never run. whether on Lists, H/VStacks, Buttons, whatever. the pdf type don't seem to work either, as well as many others. the only type that i'm able to use if fileURL, which is mainly like no restriction.
i'm not sure if i'm doing something wrong or if SwiftUI is half working for the mac.
here's the code:
List(appsToIgnore, id: \.self, selection: $selection) {
Text($0)
}
.onDrop(of: [.applicationBundle, .application], isTargeted: isTargeted) { providers in
print("hehe")
return true
}
replacing or just adding .fileURL in the UTType array makes the drop work but without any type restriction.
i've also tried to use .onInsert on a ForEach instead (https://developer.apple.com/documentation/swiftui/foreach/oninsert(of:perform:)-2whxl#), and to go through a proper DropDelegate (https://developer.apple.com/documentation/swiftui/dropdelegate#) but keep getting the same results. it would seem the SwiftUI drop for macOS is not yet working, but i can't find any official information about this. in the docs it is written macOS 11.0+ so i would expect it to work?
any info appreciated! thanks.
You need to validate manually, using DropDelegate of what kind of file is dragged over.
Here is a simplified demo of possible approach. Tested with Xcode 13 / macOS 11.6
let delegate = MyDelegate()
...
List(appsToIgnore, id: \.self, selection: $selection) {
Text($0)
}
.onDrop(of: [.fileURL], delegate: delegate) // << accept file URLs
and verification part like
class MyDelegate: DropDelegate {
func validateDrop(info: DropInfo) -> Bool {
// find provider with file URL
guard info.hasItemsConforming(to: [.fileURL]) else { return false }
guard let provider = info.itemProviders(for: [.fileURL]).first else { return false }
var result = false
if provider.canLoadObject(ofClass: String.self) {
let group = DispatchGroup()
group.enter() // << make decoding sync
// decode URL from item provider
_ = provider.loadObject(ofClass: String.self) { value, _ in
defer { group.leave() }
guard let fileURL = value, let url = URL(string: fileURL) else { return }
// verify type of content by URL
let flag = try? url.resourceValues(forKeys: [.contentTypeKey]).contentType == .applicationBundle
result = flag ?? false
}
// wait a bit for verification result
_ = group.wait(timeout: .now() + 0.5)
}
return result
}
func performDrop(info: DropInfo) -> Bool {
// handling code is here
return true
}
}
When I use Xcode 12 to create a "Document App", the app template that is generated is one where the CoreData-backed "Document" represents the current tab, as seen below:
So basically if I hit cmd-S, the semantics are the to save the content of that one currently-active tab.
However, what if I wanted the "Document" to represent all the tabs in that window? Given that these default window tabs are sort of baked in, is Cocoa flexible enough to fit my design criteria?
The sample you've posted contains multiple documents (Untitled, Untitled 2, ..) inside a single window. Each of these tabs is a separate document with the tabbed interface handled transparently by macOS.
If you'd like to use tabs inside a single document - like e.g. sheets in a Numbers document - you'd have to implement that functionality on your own.
When a window tab is moved, the tabGroup property of the window changes. The tabGroup property is observable but this is not documented. Window controllers can be moved to another document with addWindowController. I don't know how to prevent a new document from opening in a tab in another document. Accessing the tabGroup seems to work but it's a hack. Switching NSWindow.allowsAutomaticWindowTabbing off and on also seems to work. Here's my test app (Xcode app template, document based, XIB. Add a WindowController subclass and change the class of the file's owner in Document.xib.)
class Document: NSDocument {
var documentData: [String]? // String per window
func addWindowTab(_ data: String?) {
let windowController = WindowController(windowNibName: NSNib.Name("Document"))
if let text = data {
windowController.text = text
}
if let otherWindowController = windowControllers.first, // document has other window(s)
let tabgroup = otherWindowController.window?.tabGroup,
let newWindow = windowController.window {
tabgroup.addWindow(newWindow)
}
else {
_ = windowController.window?.tabGroup // access tabGroup to open new documents in a new window
windowController.showWindow(self)
}
addWindowController(windowController)
}
override func makeWindowControllers() {
if let data = documentData {
for windowData in data {
addWindowTab(windowData)
}
}
else {
addWindowTab(nil)
}
}
func windowControllerDidChangeTabGroup(_ windowController: NSWindowController) {
var destinationDocument: Document?
// check if the window is in a tabgroup with windows of another document
if let tabGroup = windowController.window?.tabGroup,
tabGroup.windows.count > 1 {
for otherWindow in tabGroup.windows {
if let otherWindowController = otherWindow.delegate as? WindowController,
otherWindowController.document !== self {
destinationDocument = otherWindowController.document as? Document
break;
}
}
}
// check if this document has other windows
else if windowControllers.count > 1 {
destinationDocument = Document()
NSDocumentController.shared.addDocument(destinationDocument!)
}
if let destinationDocument = destinationDocument,
destinationDocument !== self {
destinationDocument.addWindowController(windowController) // removes windowController from self
if windowControllers.count == 0 {
close()
}
}
}
}
class WindowController: NSWindowController {
var tabObservation: NSKeyValueObservation?
override func windowDidLoad() {
super.windowDidLoad()
tabObservation = window?.observe(\.tabGroup, options: []) { object, change in
if let document = self.document as? Document {
// accessing tabGroup can change tabGroup and cause recursion, schedule on runloop
DispatchQueue.main.async{
document.windowControllerDidChangeTabGroup(self)
}
}
}
}
override func newWindowForTab(_ sender: Any?) {
if let document = document as? Document {
document.addWindowTab(nil)
}
}
}
I created a tester app to test adding a GameCenter leaderboard to a simple SwiftUI game I am creating. I have been unable to figure out how to display the Game Center leaderboard with all the scores.
I have created a class containing all the Game Center functions (authentication and adding score to the leaderboard. This is called from the main ContentView view. I can't figure out how to make it show the leaderboard (or even the gamecenter login screen if the player isn't already logged in.)
This is my GameCenterManager class:
class GameCenterManager {
var gcEnabled = Bool() // Check if the user has Game Center enabled
var gcDefaultLeaderBoard = String() // Check the default leaderboardID
var score = 0
let LEADERBOARD_ID = "grp.colorMatcherLeaderBoard_1" //Leaderboard ID from Itunes Connect
// MARK: - AUTHENTICATE LOCAL PLAYER
func authenticateLocalPlayer() {
let localPlayer: GKLocalPlayer = GKLocalPlayer.local
localPlayer.authenticateHandler = {(ViewController, error) -> Void in
if((ViewController) != nil) {
print("User is not logged into game center")
} else if (localPlayer.isAuthenticated) {
// 2. Player is already authenticated & logged in, load game center
self.gcEnabled = true
// Get the default leaderboard ID
localPlayer.loadDefaultLeaderboardIdentifier(completionHandler: { (leaderboardIdentifer, error) in
if error != nil { print(error ?? "error1")
} else { self.gcDefaultLeaderBoard = leaderboardIdentifer! }
})
print("Adding GameCenter user was a success")
} else {
// 3. Game center is not enabled on the users device
self.gcEnabled = false
print("Local player could not be authenticated!")
print(error ?? "error2")
}
}
} //authenticateLocalPlayer()
func submitScoreToGC(_ score: Int){
let bestScoreInt = GKScore(leaderboardIdentifier: LEADERBOARD_ID)
bestScoreInt.value = Int64(score)
GKScore.report([bestScoreInt]) { (error) in
if error != nil {
print(error!.localizedDescription)
} else {
print("Best Score submitted to your Leaderboard!")
}
}
}//submitScoreToGc()
}
and here is the ContentView struct:
struct ContentView: View {
//GameCenter
init() {
self.gameCenter = GameCenterManager()
self.gameCenter.authenticateLocalPlayer()
}
#State var score = 0
var gcEnabled = Bool() //Checks if the user had enabled GameCenter
var gcDefaultLeaderboard = String() //Checks the default leaderboard ID
let gameCenter: GameCenterManager
/*End GameCenter Variables */
var body: some View {
HStack {
Text("Hello, world!")
Button(action: {
self.score += 1
print("Score increased by 10. It is now \(self.score)")
self.gameCenter.submitScoreToGC(self.score)
}) {
Text("Increase Score")
}
}
}
}
Would greatly appreciate any help in fixing the problem.
I have a fix.
I use Game Center successfully in my SwiftUI App Sound Matcher. Code snippets to follow.
The code doesn't exactly follow the SwiftUI declarative philosophy but it works perfectly. I added snippets to SceneDelegate and ContentView plus used I used a GameKitHelper class similar to the one Thomas created for his test app. I based my version on code I found on raywenderlich.com.
I actually tried using a struct conforming to UIViewControllerRepresentable as my first attempt, following the same line of thought as bg2b, however it kept complaining that the game centre view controller needed to be presented modally. Eventually I gave up and tried my current more successful approach.
For SwiftUI 1.0 and iOS 13
class SceneDelegate: UIResponder, UIWindowSceneDelegate {
let contentView = ContentView()
.environmentObject(GameKitHelper.sharedInstance) // publish enabled state
func scene(_ scene: UIScene, willConnectTo session: UISceneSession,
options connectionOptions: UIScene.ConnectionOptions) {
if let windowScene = scene as? UIWindowScene {
let window = UIWindow(windowScene: windowScene)
window.rootViewController = UIHostingController(rootView: contentView)
// new code to create listeners for the messages
// you will be sending later
PopupControllerMessage.PresentAuthentication
.addHandlerForNotification(
self,
handler: #selector(SceneDelegate
.showAuthenticationViewController))
PopupControllerMessage.GameCenter
.addHandlerForNotification(
self,
handler: #selector(SceneDelegate
.showGameCenterViewController))
// now we are back to the standard template
// generated when your project was created
self.window = window
window.makeKeyAndVisible()
}
}
// pop's up the leaderboard and achievement screen
#objc func showGameCenterViewController() {
if let gameCenterViewController =
GameKitHelper.sharedInstance.gameCenterViewController {
self.window?.rootViewController?.present(
gameCenterViewController,
animated: true,
completion: nil)
}
}
// pop's up the authentication screen
#objc func showAuthenticationViewController() {
if let authenticationViewController =
GameKitHelper.sharedInstance.authenticationViewController {
self.window?.rootViewController?.present(
authenticationViewController, animated: true)
{ GameKitHelper.sharedInstance.enabled =
GameKitHelper.sharedInstance.gameCenterEnabled }
}
}
}
// content you want your app to display goes here
struct ContentView: View {
#EnvironmentObject var gameCenter : GameKitHelper
#State private var isShowingGameCenter = false { didSet {
PopupControllerMessage
.GameCenter
.postNotification() }}
var body: some View {
VStack {
if self.gameCenter.enabled
{
Button(action:{ self.isShowingGameCenter.toggle()})
{ Text(
"Press to show leaderboards and achievements")}
}
// The authentication popup will appear when you first enter
// the view
}.onAppear() {GameKitHelper.sharedInstance
.authenticateLocalPlayer()}
}
}
import GameKit
import UIKit
// Messages sent using the Notification Center to trigger
// Game Center's Popup screen
public enum PopupControllerMessage : String
{
case PresentAuthentication = "PresentAuthenticationViewController"
case GameCenter = "GameCenterViewController"
}
extension PopupControllerMessage
{
public func postNotification() {
NotificationCenter.default.post(
name: Notification.Name(rawValue: self.rawValue),
object: self)
}
public func addHandlerForNotification(_ observer: Any,
handler: Selector) {
NotificationCenter.default .
addObserver(observer, selector: handler, name:
NSNotification.Name(rawValue: self.rawValue), object: nil)
}
}
// based on code from raywenderlich.com
// helper class to make interacting with the Game Center easier
open class GameKitHelper: NSObject, ObservableObject, GKGameCenterControllerDelegate {
public var authenticationViewController: UIViewController?
public var lastError: Error?
private static let _singleton = GameKitHelper()
public class var sharedInstance: GameKitHelper {
return GameKitHelper._singleton
}
private override init() {
super.init()
}
#Published public var enabled :Bool = false
public var gameCenterEnabled : Bool {
return GKLocalPlayer.local.isAuthenticated }
public func authenticateLocalPlayer () {
let localPlayer = GKLocalPlayer.local
localPlayer.authenticateHandler = {(viewController, error) in
self.lastError = error as NSError?
self.enabled = GKLocalPlayer.local.isAuthenticated
if viewController != nil {
self.authenticationViewController = viewController
PopupControllerMessage
.PresentAuthentication
.postNotification()
}
}
}
public var gameCenterViewController : GKGameCenterViewController? { get {
guard gameCenterEnabled else {
print("Local player is not authenticated")
return nil }
let gameCenterViewController = GKGameCenterViewController()
gameCenterViewController.gameCenterDelegate = self
gameCenterViewController.viewState = .achievements
return gameCenterViewController
}}
open func gameCenterViewControllerDidFinish(_
gameCenterViewController: GKGameCenterViewController) {
gameCenterViewController.dismiss(
animated: true, completion: nil)
}
}
Update: For SwiftUI 2.0 and iOS 14 the code is lot easier
import GameKit
enum Authenticate
{
static func user() {
let localPlayer = GKLocalPlayer.local
localPlayer.authenticateHandler = { _, error in
guard error == nil else {
print(error?.localizedDescription ?? "")
return
}
GKAccessPoint.shared.location = .topLeading
GKAccessPoint.shared.isActive =
localPlayer.isAuthenticated
}
}
}
import SwiftUI
// content you want your app to display goes here
struct ContentView: View {
var body: some View {
Text( "Start Game")
// The authentication popup will appear when you first enter
// the view
}.onAppear() { Authenticate.user()}
}
}
EDIT 2023: as mentioned in comments, GKScore is now deprecated. I don't have an updated solution to present.
Partial answer for you here. I'm able to download leaderboard scores and display them in a SwiftUI list provided the device (or simulator) is logged into iCloud and has GameCenter already enabled in settings. I have not attempted to make a gameCenter authentication view controller appear if that is not the case.
Thank you for the code in your question. I used your GameCenterManager() but put it in my AppDelegate:
let gameCenter = GameCenterManager()
Below is my ShowRankings.swift SwiftUI View. I'm able to successfully authenticate and get the scores. But I still have "anomalies". The first time I run this (in simulator) I get the expected "User is not logged into Game Center" error indicating the ViewController in your GameCenterManager is not nil (I never even attempt to display it). But then I'm able to successfully get the scores and display them in a list.
import SwiftUI
import GameKit
struct ShowRankings: View {
let appDelegate = UIApplication.shared.delegate as! AppDelegate
let leaderBoard = GKLeaderboard()
#State var scores: [GKScore] = []
var body: some View {
VStack {
Button(action: {
self.updateLeader()
}) {
Text("Refresh leaderboard")
}
List(scores, id: \.self) { score in
Text("\(score.player.alias) \(score.value)")
}
}.onAppear() {
self.appDelegate.gameCenter.authenticateLocalPlayer()
self.updateLeader()
}
}
func updateLeader() {
let leaderBoard: GKLeaderboard = GKLeaderboard()
leaderBoard.identifier = "YOUR_LEADERBOARD_ID_HERE"
leaderBoard.timeScope = .allTime
leaderBoard.loadScores { (scores, error) in
if let error = error {
debugPrint("leaderboard loadScores error \(error)")
} else {
guard let scores = scores else { return }
self.scores = scores
}
}
}
}
An alternative solution is to create a UIViewControllerRepresentable for GameCenter which takes a leaderboard ID to open. This makes it simple to open a specific leader board.
public struct GameCenterView: UIViewControllerRepresentable {
let viewController: GKGameCenterViewController
public init(leaderboardID : String?) {
if leaderboardID != nil {
self.viewController = GKGameCenterViewController(leaderboardID: leaderboardID!, playerScope: GKLeaderboard.PlayerScope.global, timeScope: GKLeaderboard.TimeScope.allTime)
}
else{
self.viewController = GKGameCenterViewController(state: GKGameCenterViewControllerState.leaderboards)
}
}
public func makeUIViewController(context: Context) -> GKGameCenterViewController {
let gkVC = viewController
gkVC.gameCenterDelegate = context.coordinator
return gkVC
}
public func updateUIViewController(_ uiViewController: GKGameCenterViewController, context: Context) {
return
}
public func makeCoordinator() -> GKCoordinator {
return GKCoordinator(self)
}
}
public class GKCoordinator: NSObject, GKGameCenterControllerDelegate {
var view: GameCenterView
init(_ gkView: GameCenterView) {
self.view = gkView
}
public func gameCenterViewControllerDidFinish(_ gameCenterViewController: GKGameCenterViewController) {
gameCenterViewController.dismiss(animated: true, completion: nil)
}
}
To use just add the below wherever it is needed to display a leaderboard.
GameCenterView(leaderboardID: "leaderBoardID")
I've been looking through the docs with each beta but haven't seen a way to make a traditional paged ScrollView. I'm not familiar with AppKit so I am wondering if this doesn't exist in SwiftUI because it's primarily a UIKit construct. Anyway, does anyone have an example of this, or can anyone tell me it's definitely impossible so I can stop looking and roll my own?
You can now use a TabView and set the .tabViewStyle to PageTabViewStyle()
TabView {
View1()
View2()
View3()
}
.tabViewStyle(PageTabViewStyle())
As of Beta 3 there is no native SwiftUI API for paging. I've filed feedback and recommend you do the same. They changed the ScrollView API from Beta 2 to Beta 3 and I wouldn't be surprised to see a further update.
It is possible to wrap a UIScrollView in order to provide this functionality now. Unfortunately, you must wrap the UIScrollView in a UIViewController, which is further wrapped in UIViewControllerRepresentable in order to support SwiftUI content.
Gist here
class UIScrollViewViewController: UIViewController {
lazy var scrollView: UIScrollView = {
let v = UIScrollView()
v.isPagingEnabled = true
return v
}()
var hostingController: UIHostingController<AnyView> = UIHostingController(rootView: AnyView(EmptyView()))
override func viewDidLoad() {
super.viewDidLoad()
self.view.addSubview(self.scrollView)
self.pinEdges(of: self.scrollView, to: self.view)
self.hostingController.willMove(toParent: self)
self.scrollView.addSubview(self.hostingController.view)
self.pinEdges(of: self.hostingController.view, to: self.scrollView)
self.hostingController.didMove(toParent: self)
}
func pinEdges(of viewA: UIView, to viewB: UIView) {
viewA.translatesAutoresizingMaskIntoConstraints = false
viewB.addConstraints([
viewA.leadingAnchor.constraint(equalTo: viewB.leadingAnchor),
viewA.trailingAnchor.constraint(equalTo: viewB.trailingAnchor),
viewA.topAnchor.constraint(equalTo: viewB.topAnchor),
viewA.bottomAnchor.constraint(equalTo: viewB.bottomAnchor),
])
}
}
struct UIScrollViewWrapper<Content: View>: UIViewControllerRepresentable {
var content: () -> Content
init(#ViewBuilder content: #escaping () -> Content) {
self.content = content
}
func makeUIViewController(context: Context) -> UIScrollViewViewController {
let vc = UIScrollViewViewController()
vc.hostingController.rootView = AnyView(self.content())
return vc
}
func updateUIViewController(_ viewController: UIScrollViewViewController, context: Context) {
viewController.hostingController.rootView = AnyView(self.content())
}
}
And then to use it:
var body: some View {
GeometryReader { proxy in
UIScrollViewWrapper {
VStack {
ForEach(0..<1000) { _ in
Text("Hello world")
}
}
.frame(width: proxy.size.width) // This ensures the content uses the available width, otherwise it will be pinned to the left
}
}
}
Apple's official tutorial covers this as an example. I find it easy to follow and suitable for my case. I really recommend you check this out and try to understand how to interface with UIKit. Since SwiftUI is so young, not every feature in UIKit would be covered at this moment. Interfacing with UIKit should address most if not all needs.
https://developer.apple.com/tutorials/swiftui/interfacing-with-uikit
Not sure if this helps your question but for the time being while Apple is working on adding a Paging View in SwiftUI I've written a utility library that gives you a SwiftUI feel while using a UIPageViewController under the hood tucked away.
You can use it like this:
Pages {
Text("Page 1")
Text("Page 2")
Text("Page 3")
Text("Page 4")
}
Or if you have a list of models in your application you can use it like this:
struct Car {
var model: String
}
let cars = [Car(model: "Ford"), Car(model: "Ferrari")]
ModelPages(cars) { index, car in
Text("The \(index) car is a \(car.model)")
.padding(50)
.foregroundColor(.white)
.background(Color.blue)
.cornerRadius(10)
}
You can simply track state using .onAppear() to load your next page.
struct YourListView : View {
#ObservedObject var viewModel = YourViewModel()
let numPerPage = 50
var body: some View {
NavigationView {
List(viewModel.items) { item in
NavigationLink(destination: DetailView(item: item)) {
ItemRow(item: item)
.onAppear {
if self.shouldLoadNextPage(currentItem: item) {
self.viewModel.fetchItems(limitPerPage: self.numPerPage)
}
}
}
}
.navigationBarTitle(Text("Items"))
.onAppear {
guard self.viewModel.items.isEmpty else { return }
self.viewModel.fetchItems(limitPerPage: self.numPerPage)
}
}
}
private func shouldLoadNextPage(currentItem item: Item) -> Bool {
let currentIndex = self.viewModel.items.firstIndex(where: { $0.id == item.id } )
let lastIndex = self.viewModel.items.count - 1
let offset = 5 //Load next page when 5 from bottom, adjust to meet needs
return currentIndex == lastIndex - offset
}
}
class YourViewModel: ObservableObject {
#Published private(set) items = [Item]()
// add whatever tracking you need for your paged API like next/previous and count
private(set) var fetching = false
private(set) var next: String?
private(set) var count = 0
func fetchItems(limitPerPage: Int = 30, completion: (([Item]?) -> Void)? = nil) {
// Do your stuff here based on the API rules for paging like determining the URL etc...
if items.count == 0 || items.count < count {
let urlString = next ?? "https://somePagedAPI?limit=/(limitPerPage)"
fetchNextItems(url: urlString, completion: completion)
} else {
completion?(pokemon)
}
}
private func fetchNextItems(url: String, completion: (([Item]?) -> Void)?) {
guard !fetching else { return }
fetching = true
Networking.fetchItems(url: url) { [weak self] (result) in
DispatchQueue.main.async { [weak self] in
self?.fetching = false
switch result {
case .success(let response):
if let count = response.count {
self?.count = count
}
if let newItems = response.results {
self?.items += newItems
}
self?.next = response.next
case .failure(let error):
// Error state tracking not implemented but would go here...
os_log("Error fetching data: %#", error.localizedDescription)
}
}
}
}
}
Modify to fit whatever API you are calling and handle errors based on your app architecture.
Checkout SwiftUIPager. It's a pager built on top of SwiftUI native components:
If you would like to exploit the new PageTabViewStyle of TabView, but you need a vertical paged scroll view, you can make use of effect modifiers like .rotationEffect().
Using this method I wrote a library called VerticalTabView 🔝 that turns a TabView vertical just by changing your existing TabView to VTabView.
You can use such custom modifier:
struct ScrollViewPagingModifier: ViewModifier {
func body(content: Content) -> some View {
content
.onAppear {
UIScrollView.appearance().isPagingEnabled = true
}
.onDisappear {
UIScrollView.appearance().isPagingEnabled = false
}
}
}
extension ScrollView {
func isPagingEnabled() -> some View {
modifier(ScrollViewPagingModifier())
}
}
To simplify Lorenzos answer, you can basically add UIScrollView.appearance().isPagingEnabled = true to your scrollview as below:
VStack{
ScrollView(showsIndicators: false){
VStack(spacing: 0){ // to remove spacing between rows
ForEach(1..<10){ i in
ZStack{
Text(String(i))
Circle()
} .frame(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height)
}
}
}.onAppear {
UIScrollView.appearance().isPagingEnabled = true
}
.onDisappear {
UIScrollView.appearance().isPagingEnabled = false
}
}