Swift Composable Presentation
Presentation and navigation helpers for SwiftUI applications build with ComposableArchitecture.
If you are familiar with ComposableArchitecture, you know how to build a fully-featured application from isolated components. You can combine reducers and scope stores to achieve that. However, when one component optionally embeds another one (or presents in navigation meaning), it could be tricky to handle side effects correctly.
ComposablePresentation is a library that helps to compose reducers in apps built with ComposableArchitecture. You can use it whenever you need to conditionally present a component, like when presenting a sheet, navigating between screens, or displaying a list of components. It also comes with SwiftUI helpers for sheets, navigation links, for-each-store, and other presentations.
Reducer.presenting functions allows combining the reducer with a reducer of an optionally presented component. Once the component is dismissed (its optional state changes from honest value to
nil), the effects returned by its reducer are automatically canceled.
More info about the concept can be found in the article: Thoughts on SwiftUI navigation.
🏛 Project structure
ComposablePresentation (Xcode Workspace) ├─ swift-composable-presentation (Swift Package) | └─ ComposablePresentation (Library) └─ Example (Xcode Project) └─ Example (iOS Application)
Use Swift Package Manager to add
ComposablePresentation as a dependency to your project.
This repository contains an example iOS application built with SwiftUI and ComposableArchitecture.
- Example source code is contained in the
- Run the app using the
SwiftUI example that shows how to present a sheet with content driven by a store with an optional state. The sheet is presented when the store's state has an honest value and dismisses when it becomes
nil. All effects produced by the store's reducer while the content is presented are canceled when the sheet is dismissed.
SwiftUI example that shows how to present a full-screen cover with content driven by a store with an optional state. The cover is presented when the store's state has an honest value and dismisses when it becomes
nil. All effects produced by the store's reducer while the content is presented are canceled when the cover dismisses.
SwiftUI example with
NavigationLink driven by a store with an optional state. The link is active when the store's state has an honest value, and inactive when it becomes
nil. All effects produced by the store's reducer while the content is presented are canceled when the link destination dismisses.
SwiftUI example of
selection, driven by a store with an optional state. It shows how to use store-driven
NavigationLink on a list, and present details screen when the list item is selected. All effects produced by the store's reducer are canceled when selection changes.
SwiftUI example with a list of components. When a component is deleted from the list, all effects produced by its reducer are canceled.
SwiftUI example that shows how to dismiss multiple navigation links at once (poping back to root view) in state-driven navigation. All effects produced by reducers of presented stores are canceled on dismiss.
In most cases, the presentation has a corresponding present and dismiss animations. When we drive it with an optional state, it becomes a problem. Let's say we want to programmatically dismiss a sheet, so we set its state to
nil. It triggers the dismiss animation, but due to the fact that our state is already
nil, we can't present the sheet content during this transition. As a workaround,
replayNonNil function that can be passed to the optional
mapState parameter of
View. popover, and other SwiftUI helper functions.
SwiftUI example of a component that conditionally presents one of two child components. The state is modeled as an enum with two cases. All effects produced by the child component are canceled when the child component is removed from the parent component.
- Use Xcode ≥ 13.1.
- Clone the repository or create a fork & clone it.
ComposablePresentationscheme for building the library and running unit tests.
- If you want to contribute:
- Create a pull request containing your changes or bugfixes.
- Make sure to add tests for the new/updated code.
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Copyright © 2021 Dariusz Rybicki Darrarski