extension UILabel {

func fitFontForSize(var minFontSize : CGFloat = 15.0, var maxFontSize : CGFloat = 300.0, accuracy : CGFloat = 1.0)
{
assert(maxFontSize > minFontSize)
layoutIfNeeded() // Can be removed at your own discretion
let constrainedSize = bounds.size

while maxFontSize – minFontSize > accuracy
{
let midFontSize : CGFloat = ((minFontSize + maxFontSize) / 2)
font = font.fontWithSize(midFontSize)
sizeToFit()
let checkSize : CGSize = bounds.size
if  checkSize.height < constrainedSize.height && checkSize.width < constrainedSize.width {
minFontSize = midFontSize
} else {
maxFontSize = midFontSize
}
}
font = font.fontWithSize(minFontSize)
sizeToFit()
layoutIfNeeded() // Can be removed at your own discretion
}

}