How to Pass Values from View to ViewModel in SwiftUI?

Discover how to effectively pass values like email addresses from your SwiftUI views to the corresponding ViewModel. This guide provides practical examples and step-by-step instructions.
---
This video is based on the question https://stackoverflow.com/q/69793460/ asked by the user 'New iOS Dev' ( https://stackoverflow.com/u/4622363/ ) and on the answer https://stackoverflow.com/a/69794696/ provided by the user 'workingdog support Ukraine' ( https://stackoverflow.com/u/11969817/ ) 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: How to pass value form view to view model in SwiftUI?

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 Pass Values from View to ViewModel in SwiftUI?

Passing values between views and their respective ViewModels in SwiftUI can seem daunting, especially for newcomers. Whether you are trying to grab data like user inputs or maintain states across different screens, understanding how to effectively manage these data flows is crucial. In this post, we will address a common scenario: passing an email value from a view to its corresponding ViewModel.

The Challenge

Imagine you have an email input field in your SwiftUI view. You want to capture this email and pass it to the ViewModel for further processing, like updating the server or validating the input. This is a common requirement, but the implementation details can be tricky.

Let’s take a look at the initial code setup that reflects this issue.

Initial Setup

Here’s what a typical structure might look like:

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

You might also have a ViewModel defined like this:

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

The Solution

To address the challenge of passing the email value to the ViewModel, consider a more structured approach as shown below:

Step 1: Create a Single Source of Truth

Utilize @ StateObject to declare the ViewModel in your main view. Here’s how you can set it up:

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

Step 2: Modify the View and ViewModel

Make sure your EmailViewModel uses @ Published to create a reactive binding with the view:

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

Your EmailView should observe the ViewModel and bind the text field directly to the emailText property:

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

Conclusion

By adopting this pattern, you ensure a clean separation of concerns between your view and ViewModel. The ViewModel now holds the email content, and as users type in the text field, the data is automatically updated and passed back to the ViewModel. With SwiftUI's reactive nature, you benefit from an efficient and dynamic interface that can easily respond to user inputs.

Final Thoughts

With the right setup, passing values from view to ViewModel in SwiftUI becomes straightforward. Use @ StateObject for owning the ViewModel, @ ObservedObject for observing it in child views, and @ Published to create a reactive data flow. This approach not only makes your code cleaner but also leverages SwiftUI’s powerful data-binding capabilities.

Feel free to experiment with more complex data types and interactions as you grow more comfortable with this essential concept in SwiftUI. Happy coding!