Why is the wordWrapping result is different CATextlayer and UILabel

Question

I'm trying to set the text with CATextLayer and UILabel.

Same Font, Size and Bounds but WordWrapping result is different.

Here is my code.

 let textHeaderAttributes = [
            NSAttributedStringKey.font: UIFont.boldSystemFont(ofSize: 24), // font
            NSAttributedStringKey.foregroundColor: UIColor.white,           // text color
//            NSAttributedStringKey.backgroundColor: UIColor.black
        ]



let textHeader = NSAttributedString(string: "A classic, meaningful, functional gift", attributes: textHeaderAttributes )

 //CATextLayer
    let frontHeaderText = CATextLayer()

  frontHeaderText.string = textHeader
        frontHeaderText.contentsScale = UIScreen.main.scale
        frontHeaderText.isWrapped = true
        frontHeaderText.alignmentMode = kCAAlignmentLeft
        frontHeaderText.frame = CGRect(x: 16, y: 381, width: screenSize.width - 16, height: frontHeaderTextHeight[0])
        frontLayer.addSublayer(frontHeaderText)


    //UILabel
    let rearHeaderText = UILabel()
   rearHeaderText.attributedText = textHeader
        rearHeaderText.textAlignment = .left
        rearHeaderText.lineBreakMode = NSLineBreakMode.byWordWrapping
        rearHeaderText.numberOfLines = 0
        rearHeaderText.frame = CGRect(x: 16, y: 381, width: screenSize.width - 16, height: frontHeaderTextHeight[0])
        rearLayer.addSubview(rearHeaderText)

//Calculate label's height func getLabelHeight(text:String, font:UIFont, lineNumber:Int) -> CGFloat{

    let label = UILabel()

    label.frame = CGRect(x: 0, y: 0, width: screenSize.width - 32, height: 100)
    label.text = text
    label.font = font
    label.textAlignment = NSTextAlignment.left
    label.numberOfLines = lineNumber;

    label.sizeToFit()

    return label.frame.height

}