How to resize Title in a navigation bar dynamically

Question

I have some views that show up in a navigation controller. Two of these views have a longer title for the navigation bar.

The problem is that when the title is too

Answer 1

Swift version of Accepted Answer + putting the label text on center :

Swift 2.3:

    self.title = "Your TiTle Text"
    let tlabel = UILabel(frame: CGRectMake(0, 0, 200, 40))
    tlabel.text = self.title
    tlabel.textColor = UIColor.whiteColor()
    tlabel.font = UIFont.boldSystemFontOfSize(17) //UIFont(name: "Helvetica", size: 17.0)
    tlabel.backgroundColor = UIColor.clearColor()
    tlabel.adjustsFontSizeToFitWidth = true
    tlabel.textAlignment = .Center
    self.navigationItem.titleView = tlabel

And Swift 3 :

    self.title = "Your TiTle Text"
    let frame = CGRect(x: 0, y: 0, width: 200, height: 40)
    let tlabel = UILabel(frame: frame)
    tlabel.text = self.title
    tlabel.textColor = UIColor.white
    tlabel.font = UIFont.boldSystemFont(ofSize: 17) //UIFont(name: "Helvetica", size: 17.0)
    tlabel.backgroundColor = UIColor.clear
    tlabel.adjustsFontSizeToFitWidth = true
    tlabel.textAlignment = .center
    self.navigationItem.titleView = tlabel