generateBestRepresentation(for:completion:)

Generates the best possible thumbnail representation for a file and calls a handler upon completion.

Declaration

func generateBestRepresentation(for request: QLThumbnailGenerator.Request, completion completionHandler: @escaping  @Sendable (QLThumbnailRepresentation?, (any Error)?) -> Void)

func generateBestRepresentation(for request: QLThumbnailGenerator.Request) async throws -> QLThumbnailRepresentation

Parameters

request:
The request that contains information about the thumbnail that you want to create.
completionHandler:
The completion handler to call when the thumbnail generation completes. It is always called when QLThumbnailGenerator finishes the generation of a requested thumbnail.
The completion handler takes the following parameters:
thumbnail
The most representative version of the requested thumbnail or nil if QLThumbnailGenerator was unable to generate a thumbnail.
error
An error object that indicates why the thumbnail generation failed, or nil if the thumbnail generation succeeded.

Mentioned in

Creating Quick Look Thumbnails to Preview Files in Your App

Discussion

important:

You can call this method from synchronous code using a completion handler, as shown on this page, or you can call it as an asynchronous method that has the following declaration:

func generateBestRepresentation(for request: QLThumbnailGenerator.Request) async throws -> QLThumbnailRepresentation

For information about concurrency and asynchronous code in Swift, see Calling Objective-C APIs Asynchronously.