view color or visibility issue ios

Question

i'm using storyboard in app development.

OS Version:iOS7 when i push a ViewController.View is getting blank without any visibility.

i have tried in two ways instatiating viewController by using storyboard or casual way

AboutUsViewConroller *aboutUsViewConroller=[self.storyboard instantiateViewControllerWithIdentifier:@"sampleid"];

AboutUsViewConroller *aboutUsViewConroller = [AboutUsViewConroller alloc]init];
[self.navigationController pushViewController:@"aboutUsViewConroller" animated:yes];

i have changed view Color to get rid of blank but no result

[self.view setBackgroundColor:[UIColor clearColor]];