Скачать или смотреть How to Solve the UIDocumentPickerViewController Freeze Issue on Dismissal

Learn how to effectively handle the `UIDocumentPickerViewController` in your iOS applications, ensuring smooth transitions and avoiding any unexpected freezing issues.
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Resolving the UIDocumentPickerViewController Freeze Issue

When developing iOS applications using either Objective-C or Swift, you may encounter unexpected behavior with the UIDocumentPickerViewController. A common problem is that when you present the UIDocumentPickerViewController, and then try to dismiss it, your initial view controller—like a PDFBrowserViewController—may become unresponsive or "freeze." In this guide, we'll walk through this issue and explore effective solutions to keep your app functioning smoothly.

Understanding the Problem

The freeze occurs due to the presentation context. If you open the UIDocumentPickerViewController from within a view controller (say, a PDFBrowserViewController), dismissing the document picker can create a conflict in which the parent view controller doesn't properly handle the dismissal. This leads to an application interface that appears frozen, creating a frustrating experience for users.

Solutions to the UIDocumentPickerViewController Freeze Issue

To resolve the freezing problem once you've dismissed the UIDocumentPickerViewController, consider the following solutions:

Solution 1: Direct Presentation Without Intermediate Controllers

The simplest approach is to present the UIDocumentPickerViewController directly from your root or topmost view controller instead of going through another view controller like PDFBrowserViewController. This ensures a smoother transition and proper handling of view hierarchy.

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Solution 2: Dismiss Parent Controller in Delegate Methods

If you must present UIDocumentPickerViewController from within another controller, ensure that you programmatically dismiss the parent controller right after dismissing the document picker. You can achieve this using delegate methods:

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Step-by-Step Setup for Solution 2

Conform to the UIDocumentPickerDelegate: Ensure your view controller conforms to the UIDocumentPickerDelegate and implement its methods properly.

Presenting the Document Picker:

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Implement the Delegate Method:
Implement the delegate method to handle dismissal after the document picker closes.

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Conclusion

By following the above solutions, you can effectively prevent the freezing issue associated with UIDocumentPickerViewController. Implementing a direct presentation or managing your view controller hierarchy correctly allows for a seamless user experience. Always test your app thoroughly to ensure that transitions are handled smoothly and your app remains responsive to user interactions. Happy coding!