label.font.pointSize is read-only, so I'm not sure how to change it.
Update
override func viewDidLoad() {
super.viewDidLoad()
println("font size before: \(label.font.pointSize)")
label.font = UIFont(name: label.font.fontName, size: 10.0)
println("font size after: \(label.font.pointSize)")
label.setNeedsDisplay()
}
@IBAction func tap(sender : AnyObject) {
println("Button tapped")
println("tap() font size: \(label.font.pointSize)")
}
Output:
font size before: 2.0
UILabel font size after: 10.0
Button tapped
tap() font size: 17.0
The font never draws at anything other than 17.0 points.