iOS 14 and XCode 12

SwiftUI for iOS 14 brings a new and nativ grid view that is easy to use, its called LazyVGrid:

You can start with defining an array of GridItem's. GridItems are used to specify layout properties for each column. In this case all GridItems are flexible.

LazyVGrid takes an array of GridItem's as its parameter and displays the containing views according to the defined GridItems.

import SwiftUI

struct ContentView: View {
    
    let columns = [
        GridItem(.flexible()),
        GridItem(.flexible()),
        GridItem(.flexible()),
        GridItem(.flexible())
    ]
    
    var body: some View {
        ScrollView {
            LazyVGrid(columns: columns) {
                ForEach(0...100, id: \.self) { _ in
                    Color.orange.frame(width: 100, height: 100)
                }
            }
        }
    }
}

QGrid is a small library I've created that uses the same approach as SwiftUI's List view, by computing its cells on demand from an underlying collection of identified data:

In its simplest form, QGrid can be used with just this 1 line of code within the body of your View, assuming you already have a custom cell view:

struct PeopleView: View {
  var body: some View {
    QGrid(Storage.people, columns: 3) { GridCell(person: $0) }
  }
}   

struct GridCell: View {
  var person: Person
  var body: some View {
    VStack() {
      Image(person.imageName).resizable().scaledToFit()
      Text(person.firstName).font(.headline).color(.white)
      Text(person.lastName).font(.headline).color(.white)
    }
  }
}

You can also customize the default layout configuration:

struct PeopleView: View {
  var body: some View {
    QGrid(Storage.people,
          columns: 3,
          columnsInLandscape: 4,
          vSpacing: 50,
          hSpacing: 20,
          vPadding: 100,
          hPadding: 20) { person in
            GridCell(person: person)
    }
  }
} 

Please refer to demo GIF and test app within GitHub repo:

Thinking in SwiftUI, there is a easy way :

struct MyGridView : View {
var body: some View {
    List() {
        ForEach(0..<8) { _ in
            HStack {
                ForEach(0..<3) { _ in
                    Image("orange_color")
                        .resizable()
                        .scaledToFit()
                }
            }
        }
    }
}

}

SwiftUI enough if you want,you need forgot such as UIColectionView sometimes..

XCode 11.0

After looking for a while I decided that I wanted all the convenience and performance form the UICollectionView. So I implemented the UIViewRepresentable protocol.

This example does not implement the DataSource and has a dummy data: [Int] field on the collection view. You would use a @Bindable var data: [YourData] on the AlbumGridView to automatically reload your view when the data changes.

AlbumGridView can then be used like any other view inside SwiftUI.

Code

class AlbumPrivateCell: UICollectionViewCell {
    private static let reuseId = "AlbumPrivateCell"

    static func registerWithCollectionView(collectionView: UICollectionView) {
        collectionView.register(AlbumPrivateCell.self, forCellWithReuseIdentifier: reuseId)
    }

    static func getReusedCellFrom(collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> AlbumPrivateCell{
        return collectionView.dequeueReusableCell(withReuseIdentifier: reuseId, for: indexPath) as! AlbumPrivateCell
    }

    var albumView: UILabel = {
        let label = UILabel()
        return label
    }()

    override init(frame: CGRect) {
        super.init(frame: frame)
        contentView.addSubview(self.albumView)

        albumView.translatesAutoresizingMaskIntoConstraints = false

        albumView.topAnchor.constraint(equalTo: contentView.topAnchor).isActive = true
        albumView.leftAnchor.constraint(equalTo: contentView.leftAnchor).isActive = true
        albumView.rightAnchor.constraint(equalTo: contentView.rightAnchor).isActive = true
        albumView.bottomAnchor.constraint(equalTo: contentView.bottomAnchor).isActive = true
    }

    required init?(coder: NSCoder) {
        fatalError("init?(coder: NSCoder) has not been implemented")
    }
}

struct AlbumGridView: UIViewRepresentable {
    var data = [1,2,3,4,5,6,7,8,9]

    func makeUIView(context: Context) -> UICollectionView {
        let collectionView = UICollectionView(frame: .zero, collectionViewLayout: UICollectionViewFlowLayout())
        collectionView.backgroundColor = .blue
        collectionView.translatesAutoresizingMaskIntoConstraints = false
        collectionView.dataSource = context.coordinator
        collectionView.delegate = context.coordinator

        AlbumPrivateCell.registerWithCollectionView(collectionView: collectionView)
        return collectionView
    }

    func updateUIView(_ uiView: UICollectionView, context: Context) {
        //
    }

    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }

    class Coordinator: NSObject, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
        private let parent: AlbumGridView

        init(_ albumGridView: AlbumGridView) {
            self.parent = albumGridView
        }

        // MARK: UICollectionViewDataSource

        func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
            self.parent.data.count
        }

        func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
            let albumCell = AlbumPrivateCell.getReusedCellFrom(collectionView: collectionView, cellForItemAt: indexPath)
            albumCell.backgroundColor = .red

            return albumCell
        }

        // MARK: UICollectionViewDelegateFlowLayout

        func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
            let width = collectionView.frame.width / 3
            return CGSize(width: width, height: width)
        }
    }
}