I can not add navigation item to navigation bar

I add a Navigation Bar to an view, I noticed that there is no left side arrow(Navigation Item). so I drag a Navigation Item from library to Navigation Bar, the green mark "+" displayed, but the Navigation Item was not added to the Navigation Bar actually.

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Than开发者_JS百科ks interdev

Does your navigation bar have a stack? Even without using it in a UINavigationController, you can maintain a stack of navigation controllers. I suspect that the "Back" button will only display if there's something behind your current view controller. So, try the -setItems:animated: method on your navigation bar and see if putting something behind the current view helps.