Why are NSAttributedString's attributes influencing other AttributedStrings? - swift

Question

In this case I'm setting a UILabel's attributedText with a combined NSAttributedString with different attributes for each line, and for some reason some AttributedString attributes influence the other AttributedStrings, but I thought their attributed are bound to the range of that particular AttributedString. I'm basically expecting that the NSAttributedString automatically gets its range set up when I append it to the NSMutableAttributedString.
Am I wrong?
In this case the shadows applies to the other appended AttributedStrings, in another case it is the bold font that overrides all fonts to come in the next AttributedStrings. Strange.
Here is some sample code:
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var textLabel: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
textLabel.numberOfLines = 0
textLabel.lineBreakMode = .byWordWrapping
let myShadow = NSShadow()
myShadow.shadowBlurRadius = 3
myShadow.shadowOffset = CGSize(width: 3, height: 3)
myShadow.shadowColor = UIColor.gray
let attributedText = NSMutableAttributedString(string: "")
let fatString = NSMutableAttributedString(string: "Bold", attributes: [NSAttributedString.Key.foregroundColor : UIColor.green,
NSAttributedString.Key.font : UIFont.boldSystemFont(ofSize: 16),
NSAttributedString.Key.backgroundColor : UIColor.lightGray,
NSAttributedString.Key.shadow : myShadow])
let normalString = NSAttributedString(string: "\n\nNormal", attributes: [NSAttributedString.Key.foregroundColor : UIColor.white,
NSAttributedString.Key.font : UIFont.systemFont(ofSize: 16)])
let italicString = NSAttributedString(string: "\n\nItalic", attributes: [NSAttributedString.Key.foregroundColor : UIColor.yellow,
NSAttributedString.Key.font : UIFont.italicSystemFont(ofSize: 16)])
let otherFontString = NSAttributedString(string: "\n\nBold + Italic", attributes: [NSAttributedString.Key.foregroundColor : UIColor.gray,
NSAttributedString.Key.font : UIFont(descriptor: UIFontDescriptor().withSymbolicTraits([.traitBold, .traitItalic])!, size: 16)])
let normalString2 = NSAttributedString(string: "\n\nUnderlined", attributes: [NSAttributedString.Key.underlineStyle : NSUnderlineStyle.single.rawValue,
NSAttributedString.Key.foregroundColor : UIColor.red,
NSAttributedString.Key.font : UIFont.systemFont(ofSize: 16)])
attributedText.append(fatString)
attributedText.append(normalString)
attributedText.append(italicString)
attributedText.append(otherFontString)
attributedText.append(normalString2)
textLabel.attributedText = attributedText
}
}