Apple Mach-O Linker Error Group

[pig110]

when i try to use following code i get an error can you please help me out why i got this error.

    NSURL *websocketUrl = [NSURL URLWithString:@"ws://my-great-server.com/websocket"];
    STOMPClient *client = [[STOMPClient alloc] initWithURL:websocketUrl webSocketHeaders:nil useHeartbeat:NO];
    
    [client connectWithLogin:@"mylogin"
                    passcode:@"mypassword"
           completionHandler:^(STOMPFrame *_, NSError *error) {
               if (error) {
                   NSLog(@"%@", error);
                   return;
               }
               
               // send a message
               [client sendTo:@"/queue/myqueue" body:@"Hello, iOS!"];
               // and disconnect
               [client disconnect];
           }];

Undefined symbols for architecture x86_64: "OBJC_CLASS$_STOMPClient", referenced from: objc-class-ref in ViewController.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)