在IOS中自定义UINavigationBar而不使用UINavigationController设置背景图像不起作用

I am newbie for IOS. So I have tried to customize the UINavigationBar with out using navigation controller. I have able to change the tile and background color but I have tried to setting the background image programmatically its not working.whether its possible to set background image using story board itself ? I have tried may websites in that mostly used programmatically. so any possible way to set the background image using UIStoryboard ?I am newbie for IOS. So I have tried to customi