ios - Blank Page in UIView -

i created simple app web view doesn't appear. blank page shown. .xib contains uiwebview

my file viewcontroller.h:

#import <uikit/uikit.h>  @interface testaviewcontroller : uiviewcontroller @property (strong, nonatomic) iboutlet uiwebview *webview;  @end 

my file viewcontroller.m:

#import "testaviewcontroller.h"  @interface testaviewcontroller ()  @end  @implementation testaviewcontroller  - (id)initwithnibname:(nsstring *)nibnameornil bundle:(nsbundle *)nibbundleornil {     self = [super initwithnibname:nibnameornil bundle:nibbundleornil];      if (self) {          // custom initialization     }      return self; }  - (void)viewdidload {     // additional setup after loading view, typically nib.      //load url webview     nsstring *strurl = @"http://www.google.it";     nsurl *url = [nsurl urlwithstring:strurl];     nsurlrequest *urlrequest = [nsurlrequest requestwithurl:url];     [self.webview loadrequest:urlrequest];   }  @end 

why happening? thanks.