Pretty sure that’s how it works on iOS. The app can only access its own sandboxed directory. If it wants anything else, it has to use a system provided file picker that provides a security scoped url for the selected file.

It's also how it works on macOS and even on modern Windows if you are running sandboxed apps.

Yes, UIDocumentPickerViewController is 10+ years old at this point.

There’s also a similar photos picker (PHPicker) which is especially good from 2023 on. Signal uses this for instance.

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