Solving the QLPreviewController Issue in SwiftUI TabView

Discover how to successfully integrate `QLPreviewController` for PDFs within a SwiftUI TabView. Overcome common pitfalls and enhance your app's capabilities with this detailed guide.
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This video is based on the question https://stackoverflow.com/q/77623479/ asked by the user 'JasonK' ( https://stackoverflow.com/u/18304151/ ) and on the answer https://stackoverflow.com/a/77625951/ provided by the user 'Jack Goossen' ( https://stackoverflow.com/u/4428119/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Problem: QLPreviewController in SwiftUI TabView

If you've ever tried to implement QLPreviewController in a SwiftUI TabView and found yourself facing challenges loading PDF files, you're not alone. This issue has puzzled many developers. Specifically, it arises when you attempt to use the TabView in a paging style alongside QLPreviewController.

The scenario often looks something like this:

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

The QLPreviewController is designed to preview documents like PDFs, but when embedded within a TabView, its functionality becomes impaired, particularly in a page format.

The Solution: Wrapping with NavigationStack

The primary workaround for this issue is to wrap your PreviewController within a NavigationStack inside your TabView.

Here’s how you can achieve that:

Revised Implementation

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

Breakdown of the Code:

State Variables:

@ State private var url: This holds the PDF URL you want to preview.

@ State private var tab: This keeps track of the currently selected tab.

TabView:

The TabView now contains a loop that creates instances of NavigationStack, each encasing a PreviewController.

PreviewController:

This struct is still responsible for setting up the QLPreviewController and serving the PDF through the Coordinator pattern.

Important Note:

While wrapping the PreviewController within the NavigationStack works to resolve the issue, there's an observation worth noting: if you attempt to add a NavigationStack at the level containing the TabView, the QLPreviewController will stop functioning again. This behavior appears to be a quirk within SwiftUI that developers should be aware of.

Conclusion

Integrating QLPreviewController with a SwiftUI TabView can be challenging due to a few unexpected behaviors. However, as discussed, by wrapping your PreviewController in a NavigationStack, you can effectively showcase PDF documents within your tabbed interface.

If you continue to experience problems or if you've discovered additional insights, consider reaching out to Apple or the Swift community. Collaborative troubleshooting can often reveal solutions to these nuanced issues, ensuring smoother development experiences.

For now, happy coding, and enjoy the seamless integration of PDF previews in your SwiftUI applications!

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