How to set navigation bar font colour and size

Question

I have been trying to set both the font size and the font colour of the text in my navigation bar, however I have been having issues.

Basically what seems to be happening is my two lines of code overwrite each other and I can only get them to work on their own.

Here is my code:

    self.navigationController?.navigationBar.titleTextAttributes = [NSFontAttributeName: UIFont(name: "Avenir", size: 30)]
    self.navigationController?.navigationBar.titleTextAttributes = [NSForegroundColorAttributeName: UIColor.whiteColor()]

What do I need to change so that I can change the font size and colour?

Answer 1

In swift Mandav's excellent answer could be implemented this way:

var attributes = [
    NSForegroundColorAttributeName: UIColor.greenColor(),
    NSFontAttributeName: UIFont(name: "Avenir", size: 30)!
]
self.navigationController?.navigationBar.titleTextAttributes = attributes

Note that the UIFont initializer returns an optional because it could fail to find the font, so an exclamation point is used.