startFetchingMetadata(for:completionHandler:)

Fetches metadata for the given NSURLRequest.

Declaration

func startFetchingMetadata(for request: URLRequest, completionHandler: @escaping  @Sendable (LPLinkMetadata?, (any Error)?) -> Void)

func startFetchingMetadata(for request: URLRequest) async throws -> LPLinkMetadata

Discussion

Call this method once per LPMetadataProvider instance. If you attempt to fetch metadata multiple times on a single LPMetadataProvider instance, it throws an error.

The completion handler executes on a background queue. Dispatch any necessary UI updates back to the main queue. When the completion handler returns, it deletes any file URLs returned in the resulting LPLinkMetadata.

note:

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 startFetchingMetadata(for request: URLRequest) async throws -> LPLinkMetadata

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