This repository provides a new simple way to describe routers.
I view the application flow as a tree of all possible screen states. From this point of view, navigation is the selection of a node of this tree.
Take for example an application with such a hierarchy of screens:
TabView
┌────────────┼────────────┐
Tab1 Tab2 NavigationView
┌────────┴────────┐
RootView Push1View
│
PickerView
┌───────┴───────┐
Text1 Text2PickerView is here to demonstrate that navigation can mean not only changing screens, but also changing any state of any view.
Describe your flow as a struct with Step properties:
@Steps
struct TabSteps {
var tab1
var tab2: SomeTab2Data = .init()
var tab3: NavigationSteps = .screen1
var none
}
@Steps
struct NavigationSteps {
var screen1
var screen2: PickerSteps = .none
}
@Steps
struct PickerSteps {
var text1
var text2
var none
}var steps: TabSteps = .tab1If you want to open Tab2 you need mark tab2 as selected. You have several ways to do it:
- Set
selectedproperty:
steps.selected = .tab2- Use auto-generated static functions:
steps = .tab2(SomeTab2Data())You can check which property is selected:
- With
selectedproperty:
$steps.selected == .tab2Also you can set initial selected property:
var screen3: PickerSteps = .text1Then you got a deep link for example and you need to change Tab2 to third tab with NavigationView, push to Push2View and select Text2 in PickerView.
steps.tab3.$screen2.select(with: .text2)Now tab3, screen3, text2 properties are marked as selected.
SwiftUI is a state driven framework, so it's easy to implement navigation with Steps.
StateStep updates view, stores your flow struct or binds it from parent view as an environment value. To bind flow down the view hierarchy you need use .step(...) or .stepEnvironment(...) view modifiers or initialize StateStep with Binding<Step<...>>.
stepEnvironment binds current step down the view hierarchy for embedded StateStep properties.
step modifier is just a combination of tag and stepEnvironment modifiers.
struct RootTabView: View {
@StateStep var step: TabSteps = .tab1
var body: some View {
TabView(selection: $step.selected) {
Tab1()
.step(_step.$tab1)
Tab2()
.step(_step.$tab2)
EmbededNavigation()
.step(_step.$tab3)
}
.tabViewStyle(PageTabViewStyle(indexDisplayMode: .always))
}
}
struct EmbededNavigation: View {
@StateStep var step = NavigationSteps()
var body: some View {
NavigationView {
RootView {
NavigationLink(isActive: $step.isSelected(.screen3)) {
EmbededPicker()
.stepEnvironment($step.$screen2)
} label: {
Text("push")
}
}
}
}
}
struct EmbededPicker: View {
@StateStep var step = PickerSteps()
var body: some View {
Picker("3", selection: $step.selected) {
Text("\(step.prefixString) 0")
.tag(PickerSteps.Steps.text1)
Text("\(step.prefixString) 1")
.tag(PickerSteps.Steps.text2)
}
.pickerStyle(WheelPickerStyle())
}
}You can use Step directly without StateStep wrapper, in ObservableObject view model or as a part of state in TCA Store, etc.
There is no any special instrument for UIKit, because UIKit doesn't support state driven navigation, but it's possible to use Combine to subscribe on Step changes:
let stepsSubject = CurrentValueSubject(TabSteps(.tab1))
stepsSubject
.map(\.selected)
.removeDublicates()
.sink { selected in
switch selected {
case .tab1:
...
}
}
stepsSubject.value.$tab2.select()or use didSet:
var steps = TabSteps(.tab1) {
didSet {
guard oldValue.selected != steps.selected else { return }
...
}
}@StateStep var steps = Steps()
...
NavigationLink(step: _steps.$link) {
...
} label: {
...
}@StateStep var steps = Steps()
var body: some View {
NavigationStack(path: $steps.navigationPath) {
RootView()
.navigationDestination(step: _steps.$link) {
PushView()
}
// or
.navigationDestination(for: _steps) {
switch $0 {
case .link:
PushView()
.step(_step.$link)
default:
EmptyView()
}
}
}
}Create a Package.swift file.
// swift-tools-version:5.9
import PackageDescription
let package = Package(
name: "SomeProject",
dependencies: [
.package(url: "https://github.com/dankinsoid/VDFlow.git", from: "4.27.0")
],
targets: [
.target(name: "SomeProject", dependencies: ["VDFlow"])
]
)$ swift buildDaniil Voidilov, voidilov@gmail.com
VDFlow is available under the MIT license. See the LICENSE file for more info.