swift计算文本高度

let sizing = UILabel()

sizing.numberOfLines = 3

sizing.font = messageLabel.font

sizing.text = fullText

sizing.attributedText = NSAttributedString(string: fullText)

sizing.lineBreakMode = .byTruncatingTail

let size = sizing.sizeThatFits(CGSize(width: 236, height: Double.greatestFiniteMagnitude))