横幅からWrappedなテキストが納まる領域の高さを求める方法 ref: http://qiita.com/_tid_/items/e6e959e4b82c7f478211

file0.swift

func heightForStringDrawing(myString: String, myFont: NSFont, myWidth: CGFloat) -> CGFloat
{
    var textStorage = NSTextStorage(string: myString)
    var textContainer = NSTextContainer(containerSize: NSMakeSize(myWidth, CGFloat(FLT_MAX)))
    var layoutManager = NSLayoutManager()
    layoutManager.addTextContainer(textContainer)
    textStorage.addLayoutManager(layoutManager)
    textStorage.addAttribute(NSFontAttributeName, value:myFont, range:NSMakeRange(0, textStorage.length));
    textContainer.lineFragmentPadding = 0.0

    layoutManager.glyphRangeForTextContainer(textContainer)
    return layoutManager.usedRectForTextContainer(textContainer).size.height;
}