Customized navigation controller toolbar is one pixel upper than the bottom of iPhone

Customized navigation controller toolbar is one pixel upper than the
bottom of iPhone

I had to customize UIViewController and Used following codes to customize
the UIViewController toolbar at the bottom
[self.navigationController.toolbar setBackgroundImage:[UIImage
imageWithCGImage:[UIImage imageNamed:@"List/footer.png"].CGImage scale:2
orientation:UIImageOrientationDown]
forToolbarPosition:UIToolbarPositionAny barMetrics:UIBarMetricsDefault];
[self.navigationController.toolbar setShadowImage:[UIImage
imageNamed:@"transparent.png"]
forToolbarPosition:UIToolbarPositionAny];
[self.navigationController.toolbar setBackgroundColor:[UIColor
clearColor]];

As it is obvious in screenshot picture there is one white pixel under the
customized toolbar. How can I remove the pixel?