ios - MonoTouch, ZXing: Redirect to another ViewController after scan -

i'm using zxing mobilescanner lib xamarin project ios (monotouch). set scanning, working fine, reading qrcode , having correct result. after reading qrcode want show viewcontroller. set property in second controller result scanning , want show controller.

the second view not shown on screen. no errors, no feedback, not shown. guess, mobilescanner builds own view (which can seen in source of lib) , adds navigationcontroller - , causes controller stay "behind". testing redirecting controller on button clicks working fine. tried "dispose" view calling scanner.cancel(), results in

warning: attempt dismiss view controller <uinavigationcontroller: 0x19a0c60> while presentation or dismiss in progress! 

here code, on how display view appreciated.

public override void viewdidload ()     {         base.viewdidload ();          // perform additional setup after loading view, typically nib.          scanner = new mobilebarcodescanner(this.navigationcontroller);          this.btnscan.touchupinside += (sender, e) => {              //tell our scanner use default overlay             scanner.usecustomoverlay = false;             //we can customize top , bottom text of default overlay             scanner.toptext = "ticket vor den scanner halten";             scanner.bottomtext = "code wird automatisch eingelesen";              //start scanning             scanner.scan ().continuewith((t) =>                                           {                 //our scanning finished callback                 if (t.status == system.threading.tasks.taskstatus.rantocompletion){                     string msg = "";                     zxing.result result = t.result;                      if (result != null && !string.isnullorempty (result.text)) {                          scanner.cancel();                          if(this.ticketscreen == null) {                             this.ticketscreen = new ticketscreen();                         }                           this.ticketscreen.ticketurl = result.text;                         this.navigationcontroller.pushviewcontroller(this.ticketscreen, true);                      } else {                         msg = "code nicht erkannt!";                         this.invokeonmainthread(() => {                             var av = new uialertview("fehler!", msg, null, "ok", null);                             av.show();                         });                     }                 }             });           };       } 

i use this.invokeonmainthread(() , works fine in code. solution is:

public override void viewdidload () { base.viewdidload ();

    // perform additional setup after loading view, typically nib.      scanner = new mobilebarcodescanner(this.navigationcontroller);      this.btnscan.touchupinside += (sender, e) => {          //tell our scanner use default overlay         scanner.usecustomoverlay = false;         //we can customize top , bottom text of default overlay         scanner.toptext = "ticket vor den scanner halten";         scanner.bottomtext = "code wird automatisch eingelesen";          //start scanning         scanner.scan ().continuewith((t) =>                                       {             //our scanning finished callback             if (t.status == system.threading.tasks.taskstatus.rantocompletion){                 string msg = "";                 zxing.result result = t.result;                  if (result != null && !string.isnullorempty (result.text)) {                      scanner.cancel();          this.invokeonmainthread(() =>              {               if(this.ticketscreen == null) {                     this.ticketscreen = new ticketscreen();                 }                   this.ticketscreen.ticketurl = result.text;                 this.navigationcontroller.pushviewcontroller(this.ticketscreen, true);          });                    } else {                     msg = "code nicht erkannt!";                     this.invokeonmainthread(() => {                         var av = new uialertview("fehler!", msg, null, "ok", null);                         av.show();                     });                 }             }         });       };   }