@interface _TtCC7Message25InProgressMessageDownload26AttachmentDecoderAndWriter : _TtCs12_SwiftObject {
    void /* unknown type, empty encoding */ decoder;
    void /* unknown type, empty encoding */ fileWriter;
    void /* unknown type, empty encoding */ didClose;
    void /* unknown type, empty encoding */ totalByteCount;
    void /* unknown type, empty encoding */ appendedByteCount;
}

@end