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Looking in the debug console.. and entering po problems (which is the array used in the .onAppear) I am getting:
(lldb) po problems
0 elements
This is confusing because the printIt function used in .onAppear prints the problems array fine (as shown above). Is there some kind of view Initialization problem here I am not understanding?
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Well sorry about that! At 7:00am it looked like a simple problem lol. You didn't post the Problem struct, but i assumed question is a string array.
Try this and see if this works.
import SwiftUI
struct ContentView: View {
var problems: Problem
@State private var score = 0
@State private var currentQuestion = 0
var body: some View {
ZStack {
Color.yellow
.ignoresSafeArea()
VStack {
Text("Times Table")
.font(.title)
HStack {
Text("Question \(currentQuestion)/\(problems.question.count)")
Spacer()
Text("Score: \(score)")
}
.padding(10)
Text("\(problems.question[currentQuestion])")
Spacer()
}
}
.onAppear(perform: printIt)
}
func printIt() {
print("Number of questions = \(problems.question.count)")
problems.question.forEach() { problem in
print(problem)
}
}
}
struct Problem {
let question = ["4 x 6", "4 x 7", "4 x 8", "5 x 2", "7 x 4"]
}
struct ContentView_Previews: PreviewProvider {
static private var problems = Problem()
static var previews: some View {
ContentView(problems: problems)
}
}
Hope this time it actually helps lol
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I basically just copied your code and pasted it into a new XCode project. I had to change the name of the view to ContentView and create my own Problem struct and problems array, and it seems to be working just fine. So, there doesn't seem to be a problem with the code that you have shown.
But, you don't show how your Problem struct is created or how your problems array is being passed into the view. So, I assume the problem is coming from one of those two places.
struct ContentView: View {
struct Problem {
let question: String
let answer: Int
}
@State private var score = 0
@State private var currentQuestion = 0
let problems: [Problem] = [
Problem(question: "5 x 5", answer: 25),
Problem(question: "10 x 10", answer: 100),
Problem(question: "2 x 2", answer: 4),
Problem(question: "2 x 4", answer: 8),
Problem(question: "0 x 0", answer: 0)
]
var body: some View {
ZStack {
Color.yellow
.ignoresSafeArea()
VStack {
Text("Times Table")
.font(.title)
HStack {
Text("Question \(currentQuestion)/\(problems.count)")
Spacer()
Text("Score: \(score)")
}
.padding(10)
Text("\(problems[currentQuestion].question)")
Spacer()
}
}
.onAppear(perform: printIt)
}
func printIt() {
print("Number of questions = \(problems.count)")
problems.forEach() { problem in
print(problem.question)
}
}
}
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Sorry about that.. Forgot to include Problem Struct (it was in my main ContentView)... (I also just created a GitRepo - https://github.com/TheApApp/TimesTable/tree/main to make life easier)
struct Problem {
var a = 0
var b = 0
var answer: Int {
a * b
}
var question: String {
"\(a) x \(b) = "
}
}
I do believe the problem has to be on how I pass from ContentView to GameView. I thought I could just define
var problems: [Problem]
in GameView
and when I am loading GameView, I would pass in the Array like this
GameView(problems: problems)
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Things can get a bit complicated when trying to pass an array between views and modify it in SwiftUI. But, you will learn the best ways to do that later on in this course.
For now, I would move the code for creating your problems array into your GameView since that is the place that the array will be used. That will require that you pass the selected settings (difficulty and number of questions) to your GameView though, so that it will have enough information to be able to create the array of problems on its own.
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Thanks @Fly0strich, tried to do that, still crashing on the same line... I still think it has something to do with sequence of loading view. Current full code in gitrepo
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onAppear is called when the View appears on screen. You are generating the questions at that time.
But the initial render of the body happens before the onAppear triggers, at which time your problems array is empty, so accessing index 0 causes a crash.
If you change to something like this instead, your problem should go away:
first example removed
//1. remove default values from properties
let chosenDifficulty: Int
let times: Int
//2. create an explicit init for the View
init(chosenDifficulty: Int = 0, times: Int = 2) {
self.chosenDifficulty = chosenDifficulty
self.times = times
_problems = State(wrappedValue: generateProblems())
}
//3. remove the onAppear handler
//4. tweak the generateProblems function
func generateProblems() -> [Problem] {
var p: [Problem] = []
let numberOfQuestions = [5, 10, 20]
let number = numberOfQuestions[chosenDifficulty]
for _ in 0..<number {
p.append(Problem(a: Int.random(in: 2...self.times), b: Int.random(in: 2...self.times)))
}
return p
}
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Thank you @roosterboy ... I knew it had to be a sequencing issue... just not yet covered in the course...
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