QuickLookThumbnailing: OK in iOS13, KO for iOS12

See in doc that's for iOS 13+. Why do you expect it to work for iOS 12 ?:

Framework QuickLookThumbnailing

Generate thumbnails for common file types and add a Thumbnail Extension to your app to enable others to create thumbnails of your custom files.

Hello,

thanks for your quick answer, I understand your point. From my understanding, all the thumbnail functionalities have been moved into a separated framework in iOS13 (from QuickLook to QuickLookThumbnailing) to be able to share it on macOS but I did not get that this removed support for iOS12...

Does anybody know how to support thumbnailing on both iOS12 and iOS13? I tried to link QuickLook as required and QuickLookThumbnailing as optional but I still cannot get the extension called under iOS12.

Thanks in advance for your help,

Libero

Contrary to what the framework info states, it's been deprecated.

Framework

QuickLook

func QLPreviewRequestCopyContentUTI(QLPreviewRequest!) -> Unmanaged<CFString>!

func QLPreviewRequestCopyOptions(QLPreviewRequest!) -> Unmanaged<CFDictionary>!

func QLPreviewRequestCopyURL(QLPreviewRequest!) -> Unmanaged<CFURL>!

func QLThumbnailCancel(QLThumbnail!)

func QLThumbnailCopyDocumentURL(QLThumbnail!) -> Unmanaged<CFURL>!

func QLThumbnailCopyImage(QLThumbnail!) -> Unmanaged<CGImage>!

func QLThumbnailCopyOptions(QLThumbnail!) -> Unmanaged<CFDictionary>!

func QLThumbnailCreate(CFAllocator!, CFURL!, CGSize, CFDictionary!) -> Unmanaged<QLThumbnail>!

func QLThumbnailDispatchAsync(QLThumbnail!, DispatchQueue!, (() -> Void)!)

func QLThumbnailGetContentRect(QLThumbnail!) -> CGRect

func QLThumbnailGetMaximumSize(QLThumbnail!) -> CGSize

func QLThumbnailGetTypeID() -> CFTypeID

func QLThumbnailImageCreate(CFAllocator!, CFURL!, CGSize, CFDictionary!) -> Unmanaged<CGImage>!

func QLThumbnailIsCancelled(QLThumbnail!) -> Bool

func QLThumbnailRequestCopyContentUTI(QLThumbnailRequest!) -> Unmanaged<CFString>!

func QLThumbnailRequestCopyOptions(QLThumbnailRequest!) -> Unmanaged<CFDictionary>!

func QLThumbnailRequestCopyURL(QLThumbnailRequest!) -> Unmanaged<CFURL>!

                if #available(iOS 13.0, *) {
                     // Use QLThumbnailGenerationRequest in QuickLookThumbnailing to generate thumbnails.
                } else {
                    // call QLThumbnailCreate() //  Use QuickLookThumbnailing for thumbnails.
                }

Hello,

I do not use any of the deprecated functions. What I am using is an implementation of a QLThumbnailProvider

API_AVAILABLE(ios(11.0), macos(10.15)) API_UNAVAILABLE(tvos, watchos) __attribute__((visibility("default")))
@interface QLThumbnailProvider : NSObject

/**
 Subclass this method to provide a QLThumbnailReply that either contains a drawing block or an image file URL.


 @param request An object which contains information about the thumbnail that should be provided. It contains the URL of the file to provide a thumbnail for.
 @param handler Call the completion handler with a QLThumbnailReply if you can provide a thumbnail, or with an NSError if you cannot.
                If an error is passed or reply is nil, no thumbnail will be drawn.
                The handler can be called asynchronously after the method has returned.
 */
- (void)provideThumbnailForFileRequest:(QLFileThumbnailRequest *)request completionHandler:(void (^)(QLThumbnailReply * _Nullable reply, NSError * _Nullable error))handler NS_SWIFT_NAME(provideThumbnail(for:_:));

@end

defined in QuickLookThumbnailing/QThumbnailProvider.h framework under iOS13. The same class is defined in QuickLook framework under iOS12.

I tried optional linking but does not work: extension is not called.

I also tried importing the QuickLook module and then the QuickLookThumbnailing one by using the @import statement in code with the Automatic Link Framework option on but the extension is still never called under iOS12...

I deeply regret having heavily invested into UIDocumentBrowserViewController...it's super broken on basic capabilities like this one... 😟

Libero

Did you call Developers support ? Link at the very bottom of this page

Contact Us

Thanks for the feedback.

I never noticed extension wizard. Where is it in XCode ?

Check out this link: https://developer.apple.com/documentation/quicklookthumbnailing/providing_thumbnails_of_your_custom_file_types?language=objc

"To add a Thumbnail Extension to your app, select your project in Xcode’s Project navigator and make sure the General pane is visible. Select the + button and add a new Thumbnail extension to your app. Make sure to allow Xcode to create and activate a new build scheme for the extension."

Thanks.