Thomvis

import SwiftUI

private final class StateDrivenNavigationController<V>: NSObject, UIViewControllerRepresentable, UIDocumentPickerDelegate where V: Hashable {

    let stack: [V]
    let content: (V) -> AnyView
    let onStackChanged: ([V]) -> Void

    init(stack: [V], onStackChanged: @escaping ([V]) -> Void, content: @escaping (V) -> AnyView) {
        self.stack = stack

Thomvis

import SwiftUI

struct ContentView: View {

    @State var tab = 0
    @State var selections: [Int: Int] = [:]

    var body: some View {
        ZStack {
            TabView {

Thomvis

//
//  ContentView.swift
//  FlowLayoutST
//
//  Created by Chris Eidhof on 22.08.19.
//  Copyright © 2019 Chris Eidhof. All rights reserved.
//
import SwiftUI

struct FlowLayout {

Thomvis

class ActionTarget {
    let handler: () -> Void

    init(handler: @escaping () -> Void) {
        self.handler = handler
    }

    @IBAction func handle() {
        handler()
    }

Thomvis

func ShieldIcon(ac: Int) -> some View {
    ZStack {
        Image(systemName: "shield")
            .font(.title)
        Text("\(ac)")
            .font(.caption)
    }
}

Thomvis

struct ContentView: View {
    @State var count: Int = 3

    var body: some View {
        return NavigationView {
            VStack(spacing: 50) {
                HStack {
                    Button(action: { self.count += 1 }) {
                        Text("Add")
                    }

Thomvis

struct Stack<Item>: View where Item: View {
    let items: [Item]

    init(@ViewBuilder items: () -> Item) {
        fatalError("How to get the views out of the view builder's result (TupleView) into self.items?")
    }

    var body: some View {
        fatalError("How to layout self.items in a Group/ZStack?")
        return EmptyView()

Thomvis

type loadableData('e) =
  | Loading
  | Loaded(list('e));

type loadableDataAction('e) =
  | DidLoad(list('e));

type state = {data: loadableData(Api.product)};

/* Action declaration */

Thomvis

// This view overrides safeAreaInsets in order to work around
// (possibly erroneous) behavior of UIKit where safe area insets change
// when a view is transformed. (see http://www.openradar.me/35532074)
//
// Use this view as the direct subview of the view that has the transform applied.
// This view's frame should be equal to the superview's bounds for this to work.
@objc public class TransformIgnoringSafeAreaInsetsView: UIView {
    @available(iOS 11.0, *)
    override public var safeAreaInsets: UIEdgeInsets {
        guard let superview = self.superview, superview.transform != .identity else {

Thomvis

I didn't cover backpressure because it is quite complex and - from my experience - not a core concept of reactive programming for mobile development. Some implementations do have it (e.g. RxJava), but to my knowledge none of the (big) iOS implementations, such as RxSwift and ReactiveSwift, have support for it. I use RxJava, but have never really needed its backpressure capabilities.

Adding backpressure to my minimal reactive programming implementation would require a layer of indirection that would establish the backchannel needed to allow for backpressure. It could look something like this:

o.subscribe { producer in
  producer.observe {
    // $0 is every element as it gets emitted
    producer.request(1) // makes sure the number of requested events stays 5 (requests are additive)
  }