改变标题字体）是：
$ b $ pre $ [self.navigationController.navigationBar setTitleTextAttributes：
@ {NSForegroundColorAttributeName：[UIColor redColor]，
NSFontAttributeName：[UIFont fontWithName：@mplus-1c-regularsize：21]}];


Swift：

  self.navigationController？.navigationBar.titleTextAttributes = 
 [NSForegroundColorAttributeName：UIColor.redColor（），
 NSFontAttributeName：UIFont（name：mplus-1c-regular，size：21）！ ] 
 

So i have this code that should change the nav bar title font, but it doenst

    NSDictionary *attributes = [NSDictionary dictionaryWithObjectsAndKeys:[UIFont
                                                                       fontWithName:_dataManager.optionsSettings.fontString size:14], NSFontAttributeName,
                            [UIColor whiteColor], NSForegroundColorAttributeName, nil];

[[UINavigationBar appearance] setTitleTextAttributes:attributes];

Changing the back button font with this code works just fine.

   //set backbutton font
NSDictionary *normalAttributes = [NSDictionary dictionaryWithObjectsAndKeys:
                                  [UIFont fontWithName:_dataManager.optionsSettings.fontString size:15], NSFontAttributeName,
                                  nil];
[[UIBarButtonItem appearance] setTitleTextAttributes:normalAttributes
                                            forState:UIControlStateNormal];

The correct way to change the title font (and color) is:

[self.navigationController.navigationBar setTitleTextAttributes:
 @{NSForegroundColorAttributeName:[UIColor redColor],
NSFontAttributeName:[UIFont fontWithName:@"mplus-1c-regular" size:21]}];

Swift:

self.navigationController?.navigationBar.titleTextAttributes = 
[NSForegroundColorAttributeName: UIColor.redColor(),
 NSFontAttributeName: UIFont(name: "mplus-1c-regular", size: 21)!]