I am a newbie to SwiftUI and I was trying to make a DFS (Depth First search) visualizer in SwiftUI. I have the following code.
//
// Maze.swift
// BookCore
//
// Created by Subhronil Saha on 14/04/21.
//
import Foundation
class Maze: ObservableObject {
@Published var map = [
[1, 2, 3, 4, 5, 6, 7, 8],
[9, 10, 11, 12, 13, 14, 15, 16],
[17, 18, 19, 20, 21, 22, 23, 24],
[25, 26, 27, 28, 29, 30, 31, 32],
[33, 34, 35, 36, 37, 38, 39, 40],
[41, 42, 43, 44, 45, 46, 47, 48],
[49, 50, 51, 52, 53, 54, 55, 56],
[57, 58, 59, 60, 61, 62, 63, 64]
]
@Published var visited = [
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0]
]
@Published var stack = [1]
var gameTimer: Timer?
@Published var currentNode = 1
@Published var row = 0
@Published var col = 0
var k = 1
// Constructor
public init() {
}
func markVisited(row: Int, col: Int) {
visited[row][col] = (visited[row][col] == 0) ? 1 : 0
}
func dfsUtil() -> [Int] {
var myStack: [Int] = [1]
while(myStack.count != 0) {
let topId = myStack[myStack.count-1]
myStack.removeLast()
currentNode = topId
let currRow = topId / 8
row = currRow
let currCol = topId % 8 - 1
col = currCol
if(visited[currRow][currCol] == 0) {
visited[currRow][currCol] = 1
}
if(topId - 8 > 0) {
let neighborId = topId - 8
let row = neighborId / 8
let col = neighborId % 8 - 1
if(visited[row][col] == 0) {
myStack.append(neighborId)
}
}
if(topId + 1 <= 64) {
let neighborId = (topId + 1)
let row = neighborId / 8
let col = neighborId % 8 - 1
if(visited[row][col] == 0) {
myStack.append(neighborId)
}
}
if(topId + 8 <= 64) {
let neighborId = (topId + 8)
let row = neighborId / 8
let col = neighborId % 8 - 1
if(visited[row][col] == 0) {
myStack.append(neighborId)
}
}
if(topId - 1 > 0) {
let neighborId = (topId - 1)
let row = neighborId / 8
let col = neighborId % 8 - 1
if(visited[row][col] == 0) {
myStack.append(neighborId)
}
}
}
return myStack
}
func dfs(startRow: Int, startCol: Int) {
// Add Root element
var myStack = dfsUtil()
stack = myStack
//gameTimer = Timer.scheduledTimer(timeInterval: 2, target: self, selector: #selector(dfsUtil), userInfo: nil, repeats: true)
}
}
I call the function dfs(0, 0) from MazeView.swift on a Button tap. And I am displaying colored circle buttons based on the visited matrix from the Maze class. The code runs the first iteration and then it crashes. I cannot figure out at all what is going wrong.
Please have a look at the code. Reaally thank you for the help.
//
// MazeView.swift
// BookCore
//
// Created by Subhronil Saha on 13/04/21.
//
import SwiftUI
public struct MazeView: View {
@EnvironmentObject var maze: Maze
public init() {
}
public var body: some View {
VStack(spacing: 10){
Spacer()
//MARK:- Board
ForEach(0..<8, id: \.self) { row in
HStack(spacing: 10){
ForEach(0..<8, id: \.self) { col in
if maze.visited[row][col] == 0 {
Button (action: {
withAnimation {
maze.markVisited(row: row, col: col)
}
}) {
ZStack {
Circle()
.foregroundColor(Color.white)
.frame(width: 40, height: 40, alignment: .center)
Text("\(maze.map[row][col])")
}
}
} else {
Button (action: {
withAnimation {
maze.markVisited(row: row, col: col)
}
}) {
Circle()
.fill(Color.green)
.frame(width: 40, height: 40, alignment: .center)
}
}
}
}
}
Spacer()
.frame(height: 30)
//MARK:- Action Buttons
Button(action: {
maze.dfs(startRow: 1, startCol: 1)
}) {
ZStack {
Capsule()
.fill(Color.pink)
.frame(width: 50, height: 20, alignment: .center)
Text("DFS")
.foregroundColor(Color.white)
}
}
Text("\(maze.currentNode)")
Text("\(maze.row)")
Text("\(maze.col)")
HStack(spacing: 10) {
ForEach(0..<maze.stack.count, id: \.self) { index in
Text("\(maze.stack[index])")
}
}
Spacer()
}
}
}