SwiftUI: ScrollView pager

ContentView.swift

//
//  ContentView.swift
//  PaginatedScrollView
//
//  Created by Aleksey Ozerov on 24.10.2019.
//  Copyright © 2019 Aleksey Ozerov. All rights reserved.
//

import SwiftUI

struct Page: View, Identifiable {
    let id = UUID()

    var body: some View {
        VStack(spacing: 0) {
            Text("Page")
        }
        .frame(width: 414, height: 300, alignment: .leading)
        .background(getRandomColor())
    }
}

struct SwiftUIPagerView<Content: View & Identifiable>: View {

    @State private var index: Int = 0
    @State private var offset: CGFloat = 0

    var pages: [Content]

    var body: some View {
        GeometryReader { geometry in
            ScrollView(.horizontal, showsIndicators: false) {
                HStack(alignment: .center, spacing: 0) {
                    ForEach(self.pages) { page in
                        page
                            .frame(width: geometry.size.width, height: nil)
                    }
                }
            }
            .content.offset(x: self.offset)
            .frame(width: geometry.size.width, height: nil, alignment: .leading)
            .gesture(DragGesture()
                .onChanged({ value in
                    self.offset = value.translation.width - geometry.size.width * CGFloat(self.index)
                })
                .onEnded({ value in
                    if abs(value.predictedEndTranslation.width) >= geometry.size.width / 2 {
                        var nextIndex: Int = (value.predictedEndTranslation.width < 0) ? 1 : -1
                        nextIndex += self.index
                        self.index = nextIndex.keepIndexInRange(min: 0, max: self.pages.endIndex - 1)
                    }
                    withAnimation { self.offset = -geometry.size.width * CGFloat(self.index) }
                })
            )
        }
    }
}

struct ContentView: View {
    var body: some View {
        SwiftUIPagerView(
            pages: (0..<4).map {
                index in Page()
        })
    }
}

extension Int {
    func keepIndexInRange(min: Int, max: Int) -> Int {
        switch self {
            case ..<min: return min
            case max...: return max
            default: return self
        }
    }
}

func getRandomColor() -> Color {
    let r = Double.random(in: 0..<1)
    let g = Double.random(in: 0..<1)
    let b = Double.random(in: 0..<1)
    return Color(red: r, green: g, blue: b, opacity: 1.0)
}

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

Your solution has unnecessary code. You can drop the ScrollView and the call to content entirely. The ScrollView is discarded as soon as you call content and build the view hierarchy on that. ;)

It seems that you are right, Adrian. Thanks.