Add an element to an array in Swift

Suppose I have an array, for example:

var myArray = ["Steve", "Bill", "Linus", "Bret"]

And later I want to push/append an element to the end of said array, to get:

["Steve", "Bill", "Linus", "Bret", "Tim"]

What method should I use?

And what about the case where I want to add an element to the front of the array? Is there a constant time unshift?