Скачать или смотреть How to Update @ State Variables in SwiftUI from Different Views?

Discover a simple method to update `@ State` variables in SwiftUI using a combination of bindings and actions. Perfect for handling dynamic data from Firebase!
---
This video is based on the question https://stackoverflow.com/q/62305623/ asked by the user 'Bobbify' ( https://stackoverflow.com/u/13719915/ ) and on the answer https://stackoverflow.com/a/62312458/ provided by the user 'NikzJon' ( https://stackoverflow.com/u/2382813/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: SwiftUI - How to update @ state variable from another view with a string from Firebase?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Update @ State Variables in SwiftUI from Different Views?

Managing state in SwiftUI can often feel complex, especially when you want to update a variable from a different view. A common scenario is needing to update an @ State variable in a main view based on user actions or external data, such as data fetched from Firebase. In this guide, we will explore a practical solution to update a @ State variable from another view seamlessly.

The Problem

Imagine you have a main view (ContentView) that displays a button. Upon clicking this button, a modal view (RaceModalView) appears, showing a list of races fetched from Firebase. Each race can change the country state variable on the main view. However, the country data from Firebase is not stored as a binding variable, which leads to complications when attempting to update the main state.

Here's a brief overview of the views involved:

ContentView: Main view that holds the state variable.

RaceModalView: Displays a list of race options and uses the country from Firebase.

RaceView: Each race option that acts as a button to select a country.

Example of ContentView

[[See Video to Reveal this Text or Code Snippet]]

Challenge When Using RaceModalView

The main challenge arises within RaceModalView, where you attempt to pass a regular string (the country from Firebase) to RaceView, but it expects a binding variable. This results in an error that states: Cannot convert value of type 'String' to expected argument type 'Binding String '.

The Solution

Step 1: Utilize Actions to Update Binding

To effectively update the country from the selected race, you can pass an action closure to the RaceView. Whenever a race is selected, you execute this action to update the country variable in ContentView.

Here’s how to implement it:

Updated RaceModalView

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Modify the RaceView to Accept Actions

The RaceView needs to be modified to accept this action. This modification allows RaceView to execute the action when its button is pressed.

Updated RaceView

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By adding an action closure to RaceView and invoking it when a race is selected, you can efficiently update the @ State variable in your main ContentView. This method not only provides clarity but also keeps your state management organized and consistent with SwiftUI's reactive framework.

Now, when a user selects a race name, the country name in the main view updates accordingly without running into type conversion errors. If you're working with dynamic data in SwiftUI, understanding how to leverage bindings and actions will greatly enhance your app's interactivity!

Happy coding!