为了使Rajneesh071的代码完整，你可能还想设置导航栏的标题颜色(和字体，如果你想要的话)，因为默认行为从iOS 6改变到7:

NSArray *ver = [[UIDevice currentDevice].systemVersion componentsSeparatedByString:@"."];
if ([[ver objectAtIndex:0] intValue] >= 7)
{
    self.navigationController.navigationBar.barTintColor = [UIColor blackColor];
    self.navigationController.navigationBar.translucent = NO;
    NSMutableDictionary *textAttributes = [[NSMutableDictionary alloc] initWithDictionary:mainNavController.navigationBar.titleTextAttributes];
    [textAttributes setValue:[UIColor whiteColor] forKey:UITextAttributeTextColor];
    self.navigationController.navigationBar.titleTextAttributes = textAttributes;
}
else
{
    self.navigationController.navigationBar.tintColor = [UIColor blackColor];
}

#define _kisiOS7 ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0)


  if (_kisiOS7)
    {
        [[UINavigationBar appearance] setBarTintColor:[UIcolor redcolor]];
    }
    else
    {
        [[UINavigationBar appearance] setBackgroundColor:[UIcolor blackcolor]];
        [[UINavigationBar appearance] setTintColor:[UIcolor graycolor]];
    }

为了使Rajneesh071的代码完整，你可能还想设置导航栏的标题颜色(和字体，如果你想要的话)，因为默认行为从iOS 6改变到7:

NSArray *ver = [[UIDevice currentDevice].systemVersion componentsSeparatedByString:@"."];
if ([[ver objectAtIndex:0] intValue] >= 7)
{
    self.navigationController.navigationBar.barTintColor = [UIColor blackColor];
    self.navigationController.navigationBar.translucent = NO;
    NSMutableDictionary *textAttributes = [[NSMutableDictionary alloc] initWithDictionary:mainNavController.navigationBar.titleTextAttributes];
    [textAttributes setValue:[UIColor whiteColor] forKey:UITextAttributeTextColor];
    self.navigationController.navigationBar.titleTextAttributes = textAttributes;
}
else
{
    self.navigationController.navigationBar.tintColor = [UIColor blackColor];
}

做最初的问题——得到旧的Twitter的导航栏外观，蓝色背景和白色文本——很容易做到，只需要使用Xcode中的界面生成器。

Using the Document Outline, select your Navigation Bar. In the Attributes Inspector, in the Navigation Bar group, change the Style from Default to Black. This changes the background colour of the Navigation and Status bars to black, and their text to white. So the battery and other icons and text in the status bar will look white when the app is running. In the same Navigation Bar group, change the Bar Tint to the colour of your liking. If you have Bar Button items in your Navigation Bar, those will still show their text in the default blue colour, so in the Attributes Inspector, View group, change the Tint to White Colour.

这应该能让你得到你想要的。下面是一个截图，可以让你更容易地看到在哪里进行更改。

注意，只改变条形颜色不会改变导航栏或状态栏的文本颜色。样式也需要改变。

如果你想使用十六进制代码，这里是最好的方法。

首先，在类的顶部定义它:

#define UIColorFromRGB(rgbValue) [UIColor colorWithRed:((float)((rgbValue & 0xFF0000) >> 16))/255.0 green:((float)((rgbValue & 0xFF00) >> 8))/255.0 blue:((float)(rgbValue & 0xFF))/255.0 alpha:1.0]

然后在“application didFinishLaunchingWithOptions”里面，放这个:

[[UINavigationBar appearance] setBarTintColor:UIColorFromRGB(0x00b0f0)];

把十六进制代码放在00b0f0的位置。

它实际上比我在这里看到的答案更简单:

1) Just make sure you select the navigation bar on the Navigation control. 
2) Select the color you want in the bar tint.
3) You have other options too, and/or individually on each view (just play with it).

我希望这能帮助到一些人。我不喜欢我看到的答案。我喜欢让我的代码尽可能的干净。并不是说用编程的方式做这件事是错误的，但确实有像我这样的人....这是给你们的。