Changing the Font of Navigation Bar Title
ou can customize the text style by using the “titleTextAttributes” properties of the navigation bar. You can specify the font, text color, text shadow color, and text shadow offset for the title in the text attributes dictionary, using the following text attribute keys:

UITextAttributeFont – Key to the font
UITextAttributeTextColor – Key to the text color
UITextAttributeTextShadowColor – Key to the text shadow color
UITextAttributeTextShadowOffset – Key to the offset used for the text shadow