Calling a navigation view from another view Swift 5 - uinavigationcontroller

I am trying to call a navigation view from another view using a navigation bar. However, when I try to call it it just comes up blank. I think something goes wrong if I call a view that has a navigation view on it. The view I'm trying to call is TeamList(). I tried calling other views and it works, but only TeamList() doesn't work since it has navigation view on it. Any ideas?
Here is the View I am trying to call
import SwiftUI
struct TeamList: View {
init() {
UITableView.appearance().backgroundColor = UIColor(.pink)
UITableViewCell.appearance().backgroundColor = UIColor(.pink)
UITableView.appearance().tableFooterView = UIView()
}
var body: some View {
NavigationView {
List(teamData) { team in
NavigationLink(destination: TeamDetail(team: team)) {
TeamRow(team: team)
}
}
.navigationBarTitle(Text("Club List"))
}
}
}
struct TeamList_Previews: PreviewProvider {
static var previews: some View {
TeamList()
}
}
And here is the view I am calling it from
import SwiftUI
struct ContentView: View {
var body: some View {
CustomNaviagtionBar()
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
struct Home : View {
var body: some View {
VStack {
HStack {
Image("epl")
VStack(alignment: .leading) {
Text("Premier League")
Text("See the latest matches")
}
.padding(.top, 40)
Spacer()
}
Spacer()
}.background(Color.pink).edgesIgnoringSafeArea(.all).foregroundColor(.white)
}
}
var tabs = ["Home","Ranking","Clubs"]
struct BarButton : View {
var image : String
#Binding var Tab : String
var body: some View {
Button(action: {Tab = image}) {
Image(image)
.renderingMode(.template)
.foregroundColor(Tab == image ? Color(.blue) : Color.black.opacity(0.4))
.padding()
}
}
}
struct CustomNaviagtionBar : View {
#State var Tab = "Home"
#State var edge = UIApplication.shared.windows.first?.safeAreaInsets
var body: some View {
ZStack(alignment: Alignment(horizontal: .center, vertical: .bottom)){
TabView(selection: $Tab) {
Home()
.tag("Home")
Ranking()
.tag("Ranking")
Clubs()
.tag("Clubs")
}
.tabViewStyle(PageTabViewStyle(indexDisplayMode: .never))
.ignoresSafeArea(.all, edges: .bottom)
HStack(spacing: 0){
ForEach(tabs, id: \.self){image in
BarButton(image: image, Tab: $Tab)
if image != tabs.last{
Spacer(minLength: 0)
}
}
}
}
}
}
struct Ranking : View {
var body: some View{
VStack{
Text("Ranking")
}
}
}
struct Clubs : View {
var body: some View{
TeamList() // This is the view that I am trying to call but come up blank
}
}

Related

Every time view is seen, the name keeps on adding to itself

I know that this sounds a bit dumb, but how do you call a function only once. I have a tab bar at the bottom of my app, and every time that it is called, the name that I got from my firebase database, keeps on being added. For example, the name in firebase is Bob. The app for the first time will display Bob. Then you would click on the settings, and go back to the home view. Then the app will say BobBob, and over and over again. How do I make this stop.
Code:
import SwiftUI
import Firebase
struct HomeView: View {
#State var name = ""
var body: some View {
NavigationView {
ZStack {
VStack{
Text("Welcome \(name)")
.font(.title)
Text("Upcoming Lessions/Reservations:")
.bold()
.padding()
Divider()
}
}
}
.navigationTitle("Home")
.onAppear(perform: {
downloadNameServerData()
})
}
private func downloadNameServerData() {
let db = Firestore.firestore()
db.collection("users").addSnapshotListener {(snap, err) in
if err != nil{
print("\(String(describing: err))")
return
}
for i in snap!.documentChanges {
_ = i.document.documentID
if let Name = i.document.get("Name") as? String {
DispatchQueue.main.async {
name.append(Name)
print("\(name)")
}
}
}
}
}
}
struct HomeView_Previews: PreviewProvider {
static var previews: some View {
HomeView()
}
}
import SwiftUI
import Firebase
struct HomeView: View {
#State var name = ""
var body: some View {
NavigationView {
ZStack {
VStack{
Text("Welcome \(name)")
.font(.title)
Text("Upcoming Lessions/Reservations:")
.bold()
.padding()
Divider()
}
}
}
.navigationTitle("Home")
.onAppear(perform: {
downloadNameServerData()
})
}
private func downloadNameServerData() {
if !name.isEmpty { return }
let db = Firestore.firestore()
db.collection("users").addSnapshotListener {(snap, err) in
if err != nil{
print("\(String(describing: err))")
return
}
for i in snap!.documentChanges {
_ = i.document.documentID
if let Name = i.document.get("Name") as? String {
DispatchQueue.main.async {
name = Name
print("\(name)")
}
}
}
}
}
}
struct HomeView_Previews: PreviewProvider {
static var previews: some View {
HomeView()
}
}
Did you consider only loading the name if you don't have one yet?
.onAppear(perform: {
if (name == null) downloadNameServerData()
})

Result of 'HymnLyrics' initializer is unused

I have the following error in my code. Please help me why I cannot use my HymnLyrics() struct inside button action. It works for NavigationLink of destination but I don't wanna use it.
import SwiftUI
struct ContentView: View {
#EnvironmentObject var tappingSwitches: TapToggle
let zoLyrics: [Lyric] = LyricList.hymnLa.sorted { lhs, rhs in
return lhs.zoTitle < rhs.zoTitle
}
var body: some View {
ScrollView {
ForEach(zoLyrics, id: \.id) { zoLyric in
VStack {
Button(action: {
HymnLyrics(lyrics: LyricList.hymnLa)// Here is the error, I can use directly by using NavagationLink
self.tappingSwitches.isHymnTapped.toggle()
}, label: {
HStack {
Text(zoLyric.zoTitle)
.foregroundColor(Color("bTextColor"))
.lineLimit(1)
.minimumScaleFactor(0.5)
Spacer()
Text("\(zoLyric.number)")
.foregroundColor(Color("bTextColor"))
}
})
}
.frame(maxWidth: .infinity, alignment: .leading)
.padding([.leading, .bottom, .trailing])
}
}
}
}

SwiftUI using Environment Object on multiple views giving issues with Navigation

Don't know if I'm abusing the idea of environment object, but experiencing an issue when using an environment object that publishes a delayed async value. One view navigates to the next, but then the 'root' gets updated subsequently and as a result causes an 'echo', or even if that is handled a navigation problem. The issue becomes even more evident when using transitions between navigation.
Is there a correct use pattern to avoid this? Or some other solution maybe?
Any guidance will be appreciated.
Attached a condensed sample to illustrate the problem.
Xcode 12.4 ios 14.1
final class SetColor: ObservableObject {
#Published var asyncVal: Bool = false
func flipIt() {
DispatchQueue.main.asyncAfter(deadline: .now()+0.5, execute: {self.asyncVal.toggle()})
}
}
struct HomeView: View {
#StateObject var setCol: SetColor = SetColor()
#State private var navActive: Bool = false
var body: some View {
NavigationView {
ZStack {
Color(setCol.asyncVal ? .blue : .purple)
Button(action: {
setCol.flipIt()
navActive.toggle()
}, label: {
Text("Change and Move")
})
.navigationTitle("Home")
.toolbar {
ToolbarItem(placement: .navigationBarTrailing) {
NavigationLink(destination: NavChild1().environmentObject(setCol),isActive: $navActive, label: { Text("GoTo 1 >") })
}
}
}
}
}
}
struct NavChild1: View {
#EnvironmentObject var setCol: SetColor
#State private var navActive: Bool = false
var body: some View {
ZStack {
Color(setCol.asyncVal ? .yellow : .orange)
Button(action: {
setCol.flipIt()
navActive.toggle()
}, label: {
Text("Change and Move")
})
.navigationTitle("Nav 1")
.toolbar {
ToolbarItem(placement: .navigationBarTrailing) {
NavigationLink(destination: NavChild2().environmentObject(setCol),isActive: $navActive, label: { Text("GoTo 2 >") })
}
}
}
}
}
struct NavChild2: View {
#EnvironmentObject var setCol: SetColor
#State private var navActive: Bool = false
var body: some View {
ZStack {
Color(setCol.asyncVal ? .yellow : .orange)
Button(action: {
setCol.flipIt()
navActive.toggle()
}, label: {
Text("Change and Move")
})
.navigationTitle("Nav 2")
.toolbar {
ToolbarItem(placement: .navigationBarTrailing) {
NavigationLink(destination: NavChild3().environmentObject(setCol),isActive: $navActive, label: { Text("GoTo 3 >") })
}
}
}
}
}
struct NavChild3: View {
#EnvironmentObject var setCol: SetColor
#State private var navActive: Bool = false
var body: some View {
ZStack {
Color(setCol.asyncVal ? .yellow : .orange)
Button(action: {
setCol.flipIt()
navActive.toggle()
}, label: {
Text("Change and Move")
})
.navigationTitle("Nav 3")
.toolbar {
ToolbarItem(placement: .navigationBarTrailing) {
NavigationLink(destination: NavChild3().environmentObject(setCol), isActive: .constant(false), label: { Text("Go Home") })
}
}
}
}
}
struct HomeView_Previews: PreviewProvider {
static var previews: some View {
HomeView()
}
}
You do not need the deadline you put in GCD action. It causes navigation actions even if user does not press on navigation (I've tested the code in a project).
This is because you accumulate jobs in the GCD queue and when they are executed, you're in another View (due to the 0.5 stall). By the way, they cause navigation since the flip is Observed and therefore whoever listens , will execute the navigation.
Anyway, what you wanna do is change the dispatch command to this:
DispatchQueue.main.async { self.asyncVal.toggle() }
And navigation will be smoother with no extra navigation commands executed afterwards.

SwiftUI: Button in Form

I am creating a Form in SwiftUi with a section that is including a flexible number of instruction.
Next to the last instruction TextField, I am showing a "+"-Button that is extending the instructions array with a new member:
var body: some View {
NavigationView {
Form {
...
Section(header: Text("Instructions")) {
InstructionsSectionView(instructions: $recipeViewModel.recipe.instructions)
}
...
struct InstructionsSectionView: View {
#Binding var instructions: [String]
var body: some View {
ForEach(instructions.indices, id: \.self) { index in
HStack {
TextField("Instruction", text: $instructions[index])
if(index == instructions.count-1) {
addInstructionButton
}
}
}
}
var addInstructionButton: some View {
Button(action: {
instructions.append("")
}) {
Image(systemName: "plus.circle.fill")
}
}
}
Now the problem is, that the button click-area is not limited to the picture but to the whole last row. Precisely the part just around the textField, meaning if I click in it, I can edit the text, but if I click on the border somewhere, a new entry is added.
I assume that this is specific to Form {} (or also List{}), since it does not happen if I use a Button next to a text field in a "normal" set-up.
Is there something wrong with my code? Is this an expected behaviour?
I am not sure why border is getting tappable, but as a workaround I used plainButtonStyle and that seems to fix this issue, and keeps functionality intact .
struct TestView: View {
#State private var endAmount: CGFloat = 0
#State private var recipeViewModel = ["abc","Deef"]
var body: some View {
NavigationView {
Form {
Section(header: Text("Instructions")) {
InstructionsSectionView(instructions: $recipeViewModel)
}
}
}
}
}
struct InstructionsSectionView: View {
#Binding var instructions: [String]
var body: some View {
ForEach(instructions.indices, id: \.self) { index in
HStack {
TextField("Instruction", text: $instructions[index])
Spacer()
if(index == instructions.count-1) {
addInstructionButton
.buttonStyle(PlainButtonStyle())
.foregroundColor(.blue)
}
}
}
}
var addInstructionButton: some View {
Button(action: {
instructions.append("")
}) {
Image(systemName: "plus.circle.fill")
}
}
}

How to chain ObservableObject?

I have a Game-object that may hold an image. Whenever an image URL is found for a game a new instance of GameImage-object should be created. It will then fetch the image and populate the UIImage property. When this happens the UI should be updated presenting the image.
class Game: ObservableObject {
#Published var image: GameImage?
}
class GameImage: ObservableObject {
let url: URL
#Published var image: UIImage?
private var cancellable: AnyCancellable?
init(url: URL) {
self.url = url
}
func fetch() {
self.cancellable = URLSession.shared.dataTaskPublisher(for: self.url)
.map { UIImage(data: $0.data) }
.replaceError(with: nil)
.receive(on: DispatchQueue.main)
.sink(receiveValue: { [weak self] (image) in
guard let self = self else { return }
self.image = image
print(self.url)
print(self.image)
})
}
func cancel() {
cancellable?.cancel()
}
deinit {
cancel()
}
}
struct ContentView: View {
#StateObject var game = Game()
var body: some View {
VStack {
if let image = game.image?.image {
Image(uiImage: image)
} else {
Text("No image.")
}
}
.onAppear(perform: {
guard let gameImageURL = URL(string: "https://cf.geekdo-images.com/itemrep/img/oVEpcbtyWkJjIjk1peTJo6hI1yk=/fit-in/246x300/pic4884996.jpg") else { return }
game.image = GameImage(url: gameImageURL)
game.image!.fetch()
})
}
}
The problem is. After fetch is done the debug console will show that image contains an UIImage. However the UI does not update to show the image. What am I missing here?
There is much more simpler solution than chaining ObservableObject, just separate dependent part into standalone subview... and all will work automatically.
Here is possible approach. Tested with Xcode 12 / iOS 14.
struct ContentView: View {
#StateObject var game = Game()
var body: some View {
VStack {
if nil != game.image {
GameImageView(vm: game.image!)
}
}
.onAppear(perform: {
guard let gameImageURL = URL(string: "https://cf.geekdo-images.com/itemrep/img/oVEpcbtyWkJjIjk1peTJo6hI1yk=/fit-in/246x300/pic4884996.jpg") else { return }
game.image = GameImage(url: gameImageURL)
game.image!.fetch()
})
}
}
struct GameImageView: View {
#ObservedObject var vm: GameImage
var body: some View {
if let image = vm.image {
Image(uiImage: image)
} else {
Text("No image.")
}
}
}

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