ContentView.swift

Array+Extensions.swift

//
//  Array+Extensions.swift
//  GridSwiftUI
//
//  Created by Mohammad Azam on 6/11/20.
//  Copyright © 2020 Mohammad Azam. All rights reserved.
//

import Foundation

extension Array {
    
    func chunks(size: Int) -> [ArraySlice<Element>] {
        
        var chunks: [ArraySlice<Element>] = [ArraySlice<Element>]()
        
        for index in stride(from: 0, to: self.count - 1, by: size) {
            
            var chunk = ArraySlice<Element>()
            let end = index + size
            if end >= self.count {
                chunk = self[index..<self.count]
            } else {
                chunk = self[index..<end]
            }
            
            chunks.append(chunk)
            
            if (end + 1) == self.count {
                let remainingChunk = self[end..<self.count]
                chunks.append(remainingChunk)
            }
            
        }
        
        return chunks
        
    }
    
}

ContentView.swift

//
//  ContentView.swift
//  GridSwiftUI
//
//  Created by Mohammad Azam on 6/11/20.
//  Copyright © 2020 Mohammad Azam. All rights reserved.
//

import SwiftUI

struct ContentView: View {
    
    let animals = ["🐈","🐆","🦌","🦒","🦏","🐄","🐀","🦩","🦜"]
    @State private var sliderValue: CGFloat = 1
    
    var body: some View {
        NavigationView {
            
            VStack {
                
                Slider(value: $sliderValue, in: 1...8, step: 1)
                           Text(String(format: "%.0f", self.sliderValue))
                                          .font(.system(size: 20))
                                          .fontWeight(.bold)
                                          .padding()
                                          .background(Color.purple)
                                          .foregroundColor(Color.white)
                                          .clipShape(Circle())
                
                List(self.animals.chunks(size: Int(self.sliderValue)), id: \.self) { chunk in
                    ForEach(chunk, id: \.self) { animal in
                        Text(animal)
                         .font(.system(size: CGFloat(300/self.sliderValue)))
                    }
                }
            }
            
            .navigationBarTitle("Animals")
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}