NSAttributedString Drawing - How Many Lines? - ios

Question

I am drawing text within a PDF using this method:
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = .center
paragraphStyle.lineBreakMode = .byWordWrapping
let textAttributes = [
NSAttributedString.Key.paragraphStyle: paragraphStyle,
NSAttributedString.Key.font: UIFont(name: "MySpecialFont", size: 16)!,
NSAttributedString.Key.foregroundColor: UIColor.black
]
let attributedText = NSAttributedString(
string: myTextArray.first,
attributes: textAttributes
)
let textRect = CGRect(
x: 400,
y: 40,
width: 80,
height: 40
)
attributedText.draw(in: textRect)
Above draws the text fine. However, sometimes, the string passed on to it seem to be too long and go on for 3 lines instead of 2. In these cases, I want to textRect to be taller. Basically to know how many lines it would take so textRect could be adjusted.
There are several functions within NSAttributedString that gives string length, but thats the length if it was in a single line.
Is there a way to know how many lines the final attributedText would take inside textRect?

Answer 1

Use NSAttributedString.boundingRect(with:options:context:) to compute the size required. You should pass .usesLineFragmentOrigin as an option so that it'll compute it for multiple lines. Pass the width you want; the height doesn't really matter, because it'll expand the height to contain the full string, and you can use that to work out your final rectangle.
That said, from your description, it sounds like you can just make the height very large (10,000 is the usual value; but maybe you want to just give room for three lines). Since you're just drawing here; it shouldn't matter if the available rect is taller than required. It only matters if it's shorter.