Setting UILabel text to bold

How do you set the text for a UILabel to bold in Swift programmatically? My code so far:

    var label = UILabel(frame:theFrame)
    label.text = "Foo"

Use font property of UILabel:

label.font = UIFont(name:"HelveticaNeue-Bold", size: 16.0)

or use default system font to bold text:

label.font = UIFont.boldSystemFont(ofSize: 16.0)

Use attributed string:

// Define attributes
let labelFont = UIFont(name: "HelveticaNeue-Bold", size: 18)
let attributes :Dictionary = [NSFontAttributeName : labelFont]

// Create attributed string
var attrString = NSAttributedString(string: "Foo", attributes:attributes)
label.attributedText = attrString

You need to define attributes.

Using attributed string you can mix colors, sizes, fonts etc within one text