objective c - data not passing between view Controllers cannot solve -

i attempting pass string between 2 view controllers, first named detailcontroller , second videocontroller. connected button using push segue. "prepareforsegue" method being called, string returning null in videocontroller. have been stuck on problem ages , still cannot find solution. appreciated.

detailcontroller.m prepareforsegue method

- (void)prepareforsegue:(uistoryboardsegue *)segue sender:(id)sender {   nsstring *mystring=self.city.camera;     nslog(@"%@", mystring);     nsstring *see=@"what going on?";     nslog(@"%@", see);      videocontroller *video= (videocontroller *) segue.destinationviewcontroller;     video.cam= self.city.camera;  } 

videocontroller.m

#import "videocontroller.h" #import "city.h" #import "detailcontroller.h" #import "viewcontroller.h"  @interface videocontroller ()  @end  @implementation videocontroller @synthesize webview,city,cam;    - (void)viewdidload {     nsstring *see = self.cam;     nslog(@"%@", see);      [super viewdidload];     // additional setup after loading view.      [self performselector:@selector(yourmethod) withobject:nil afterdelay:10.0];          nsstring * html = [nsstring stringwithformat:@"<img name=\"cam\" src=\"%@\" width=\"110%%\"  height=\"100%%\" alt=\"live feed\" style=\"background-color: #000000\" />", cam];      [webview loadhtmlstring:html baseurl:nil];  } -(void)yourmethod {     [self.navigationcontroller popviewcontrolleranimated:yes]; }  - (void)didreceivememorywarning {     [super didreceivememorywarning];     // dispose of resources can recreated. }  @end 

here messages receiving when button pushed , segue takes place. if reading correctly (null) being returned same webview other 2 strings when should coming within different webview? totally lost problem

2014-04-21 02:20:23.093 webview[47963:1a303] http://admin:*******@192.168.1.80/video.cgi/ 2014-04-21 02:20:23.094 webview[47963:1a303] going on? 2014-04-21 02:20:23.102 webview[47963:1a303] (null) 

here videocontroller.h file, can see sam set strong, missing something?

#import <uikit/uikit.h> #import "detailcontroller.h" @class city; @interface videocontroller : uiviewcontroller{ iboutlet uiwebview *webview; iboutlet uiimageview *image;    } @property (strong,nonatomic) city *city; @property (strong, nonatomic)nsstring * cam; @property(nonatomic,retain) uiwebview *webview;   @end 

see comment:

- (void)prepareforsegue:(uistoryboardsegue *)segue sender:(id)sender {       nsstring *mystring=self.city.camera;    nslog(@"%@", mystring);    nsstring *see=@"what going on?";    nslog(@"%@", see);     videocontroller *video= (videocontroller *) segue.destinationviewcontroller;    // sure self.city.camera has value     // think assign nil video.cam    video.cam= self.city.camera; }