not able to post tweets in userwall using twitter+OAuth

I used twit开发者_如何学Pythonter Oauth and it worked perfectly fine.I was able to login using twitter oauth api.The problem is i m not able to tweet from my iphone app .I ve created a login button a textfield and a post button.cud u guys help me out.below is the code

-(IBAction)login
 {
if (engine) {
    return; 
}
engine=[[SA_OAuthTwitterEngine alloc]initOAuthWithDelegate:self];
engine.consumerKey=@"g3Fd0ZY085Z25ZNOQoznw";
engine.consumerSecret=@"SGQazb5sKTXjgb96N8tlt3ezR32Dy46LknOjxX4ktE";
UIViewController *controller=[SA_OAuthTwitterController                                            controllerToEnterCredentialsWithTwitterEngine:engine delegate:self];
if (controller) {
    [self presentModalViewController:controller animated:YES];
}

}

-(IBAction)Tweet

{

[engine sendUpdate:filed.text];

}

-(void) storeCachedTwitterOAuthData: (NSString *) data forUsername: (NSString *)username

{  
NSUserDefaults   *defaults = [NSUserDefaults standardUserDefaults];  

[defaults setObject: data forKey: @"authData"];  

[defaults synchronize];  
} 


- (NSString *) cachedTwitterOAuthDataForUsername: (NSString *) username 
 {  

 return [[NSUserDefaults standardUserDefaults] objectForKey: @"authData"];  

 }

- (void) requestSucceeded: (NSString *) requestIdentifier 
  {  
  NSLog(@"Request %@ succeeded", requestIdentifier);  
  }  

- (void) requestFailed: (NSString *) requestIdentifier withError: (NSError *) error 
  {  
  NSLog(@"Request %@ failed with error: %@", requestIdentifier, error);  

  }

Use share-kit ,it will guide through your problems.