Скачать или смотреть How to Send a Notification from UIKit to a SwiftUI View

Learn how to send notifications from UIKit to SwiftUI to trigger events like pull-to-refresh seamlessly.
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This video is based on the question https://stackoverflow.com/q/71502168/ asked by the user 'Ferrakkem Bhuiyan' ( https://stackoverflow.com/u/3231139/ ) and on the answer https://stackoverflow.com/a/71502522/ provided by the user 'Yrb' ( https://stackoverflow.com/u/7129318/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Bridging UIKit to SwiftUI: Sending Notifications on Pull-to-Refresh

In the world of iOS app development, combining UIKit and SwiftUI can often raise questions about communication between these two frameworks. One common scenario is wanting to send a notification from a UIViewController to a SwiftUI view, particularly after an event like a user pulling to refresh a list. This post will walk you through the steps to achieve this seamlessly.

The Problem: Sending Notifications from UIKit to SwiftUI

You might find yourself in a situation where you have a UIViewController that implements a pull-to-refresh functionality. When the user pulls down to refresh, you want to inform a SwiftUI view that it can update accordingly. However, you notice that using .onChange() in your SwiftUI view does not respond to the notifications from UIKit. Here's how to properly set this up.

The Solution: Using NotificationCenter

Step 1: Create a Custom Notification

First, let’s create a custom notification that can be easily recognized between UIKit and SwiftUI. This is done by extending Notification.Name:

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Step 2: Posting the Notification in UIKit

Next, when the user pulls to refresh, you need to post this notification in your UIViewController. You can do this within the method that fetches the schedule data:

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Step 3: Listening for Notifications in SwiftUI

Now that you can post the notification, it's time to handle it in your SwiftUI view. Instead of using .onChange(), which isn't suited for this purpose, use .onReceive() to listen for notifications:

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Bonus: Using onChange for Variable Updates

If your goal is to notify the SwiftUI view when a variable changes, you can use the .onChange(of:) modifier. Here’s an example of how you might integrate this:

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In this case, watchedStateVar is the state variable you're observing. Whenever it changes, the notification will also be sent.

Conclusion

Integrating UIKit and SwiftUI through notifications allows you to create responsive and interactive user experiences. By following these steps, you can effectively notify your SwiftUI views of changes happening in your UIKit components, such as a pull-to-refresh action. This approach not only enhances communication between the frameworks but also keeps your code clean and maintainable.

With this knowledge, you can confidently implement notifications in your applications, ensuring your views respond to events as expected!