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Remove the boilerplate of modal presentations in SwiftUI
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README.md

ModalPresentationView

Takes the boilerplate out of managing modal presentations in SwiftUI.

Background

SwiftUI currently provides two different ways to manage modal presentations:

  • The simplest, PresentationButton, accepts a Destination parameter and presents it over the current context. It doesn't provide a control for manual dismissal, instead appearing to rely on the interactive dismissal gesture that's part of the new default .pageSheet modal presentation style.

  • Alternatively, the more powerful presentation(_:) modifier allows you to take control of the presentation state yourself, by accepting an optional parameter of type Modal.

ModalPresentationView sits in the middle, providing a ModalPresentationButton control with the same API as PresentationButton, but additionally:

  • Unlike the presentation(_:) modifier, automatically manages the state of the modal via a new ModalNavigationView. If you're familiar with NavigationView, then you already know how to use it.

  • Provides for manual dismissal via ModalDismissButton, in addition to the existing interactive dismiss gesture.

Demo

GIF showing a demo of modal presentation and dismissal

Example code

import ModalPresentationView
import SwiftUI

struct App: View {
  var body: some View {
    ModalPresentationView {
      ModalPresentationButton(destination: DetailScreen()) {
        Text("Present")
      }
    }
  }
}

struct DetailScreen: View {
  var body: some View {
    ModalDismissButton {
      Text("Dismiss")
    }
  }
}

Installation

  1. In Xcode, open your project and navigate to File > Swift Packages > Add Package Dependency...
  2. Paste the repository URL and follow the prompts to add the library to your project.

How does it work?

Internally, ModalPresentationView defines two custom environment keys, which it then uses to communicate between the container and the buttons, regardless of where they're placed in your view hierarchy.

  • Firstly, ModalPresentationView injects a present(_:) closure into the environment using the .modalPresentAction key.

  • When tapped, ModalPresentationButton reads the closure from the environment and calls it to notify ModalPresentationView to trigger a presentation. The presentation button passes the destination view into the closure by first wrapping it in an AnyView.

  • ModalPresentationView updates its internal state to pass the destination view into the presentation(_:) view modifier. It also sets a dismiss() closure on the environment of the presented view using the .modalDismissAction environment key.

  • Finally, ModalDismissButton reads the dismiss() closure from the environment and calls it when tapped, causing ModalPresentationView to update its internal state again and remove the presented modal.

Contributing

See the CONTRIBUTING document for details about how you can contribute.

License

ModalPresentationView is Copyright (c) 2019 thoughtbot, inc. It contains free software that may be redistributed under the terms specified in the LICENSE file.

About

thoughtbot

ModalPresentationView is maintained by Adam Sharp and funded by thoughtbot, inc. The names and logos for thoughtbot are trademarks of thoughtbot, inc.

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