self.navigationItem.title=@"Extras";
[self.navigationController.navigationBar setTitleTextAttributes: [NSDictionary dictionaryWithObjectsAndKeys:[UIFont fontWithName:@"HelveticaNeue" size:21], NSFontAttributeName,[UIColor whiteColor],UITextAttributeTextColor,nil]];

方法一，设置为IB:

方法二，一行代码:

navigationController?.navigationBar.barTintColor = UIColor.blackColor()

从ios5开始，我们必须使用titleTextAttribute字典(UInavigation控制器类引用中的预定义字典)设置标题文本的颜色和导航栏的字体。

 [[UINavigationBar appearance] setTitleTextAttributes:
 [NSDictionary dictionaryWithObjectsAndKeys:
  [UIColor blackColor],UITextAttributeTextColor, 
[UIFont fontWithName:@"ArialMT" size:16.0], UITextAttributeFont,nil]];

要设置标题的字体大小，我使用了以下条件..也许对任何人都有帮助

if ([currentTitle length]>24) msize = 10.0f;
    else if ([currentTitle length]>16) msize = 14.0f;
    else if ([currentTitle length]>12) msize = 18.0f;

self.navigationItem.title=@"Extras";
[self.navigationController.navigationBar setTitleTextAttributes: [NSDictionary dictionaryWithObjectsAndKeys:[UIFont fontWithName:@"HelveticaNeue" size:21], NSFontAttributeName,[UIColor whiteColor],UITextAttributeTextColor,nil]];

在IOS 7和8中，你可以将标题的颜色改为绿色

self.navigationController.navigationBar.titleTextAttributes = [NSDictionary dictionaryWithObject:[UIColor greenColor] forKey:NSForegroundColorAttributeName];