QLThumbnailProvider An abstract base class for creating thumbnails of custom file types. Declarationclass QLThumbnailProvider Mentioned inProviding Thumbnails of Your Custom File Types TopicsEssentialsprovideThumbnail(for:_:) RelationshipsInherits FromNSObjectConforms ToCVarArgCustomDebugStringConvertibleCustomStringConvertibleEquatableHashableNSObjectProtocol See AlsoThumbnails for Custom File TypesProviding Thumbnails of Your Custom File TypesQLFileThumbnailRequestQLThumbnailReply