Revision control
Copy as Markdown
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
import LinkPresentation
import UIKit
protocol HeroImageFetcher {
/// FetchHeroImage using metadataProvider needs the main thread, hence using @MainActor for it.
/// LPMetadataProvider is also a one shot object that we need to throw away once used.
/// - Parameters:
/// - siteURL: the url to fetch the hero image with
/// - metadataProvider: LPMetadataProvider
/// - Returns: the hero image
@MainActor
func fetchHeroImage(from siteURL: URL, metadataProvider: LPMetadataProvider) async throws -> UIImage
}
extension HeroImageFetcher {
@MainActor
func fetchHeroImage(from siteURL: URL,
metadataProvider: LPMetadataProvider = LPMetadataProvider()
) async throws -> UIImage {
try await fetchHeroImage(from: siteURL, metadataProvider: metadataProvider)
}
}
class DefaultHeroImageFetcher: HeroImageFetcher {
@MainActor
func fetchHeroImage(from siteURL: URL,
metadataProvider: LPMetadataProvider = LPMetadataProvider()
) async throws -> UIImage {
do {
let metadata = try await metadataProvider.startFetchingMetadata(for: siteURL)
guard let imageProvider = metadata.imageProvider else {
throw SiteImageError.unableToDownloadImage("Metadata image provider could not be retrieved.")
}
return try await imageProvider.loadObject(ofClass: UIImage.self)
} catch {
throw error
}
}
}