QLFileThumbnailRequest A request to generate a thumbnail for a custom file type. Declarationclass QLFileThumbnailRequest TopicsDescribing the Requested ThumbnailmaximumSizeminimumSizescalefileURL RelationshipsInherits FromNSObjectConforms ToCVarArgCustomDebugStringConvertibleCustomStringConvertibleEquatableHashableNSObjectProtocol See AlsoThumbnails for Custom File TypesProviding Thumbnails of Your Custom File TypesQLThumbnailProviderQLThumbnailReply