通常给UILabel设置文本，我们都是设置属性UILabel.text。这意味着显示的文本是单一的，整个文本只能有一种同样的文本效果。而另外一个属性UILabel.attributedText，就可以可以分段设置的不同的字体、阴影效果等，比如前几个字为一个阴影效果，后几个字使用下划线效果。

如下代码我做了些改变，以便在Swift 3.0上可以运行，本来的代码来自 https://makeapppie.com/2016/07/05/using-attributed-strings-in-swift-3-0/ ，

可以运行起来，查看效果：

import UIKit
@UIApplicationMain
class AppDelegate: UIResponder,UIApplicationDelegate {
    var window: UIWindow?
    func application(_ application: UIApplication,didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        self.window = UIWindow(frame: UIScreen.main.bounds)
        let page = Page()
        page.view.backgroundColor = .white
        self.window!.rootViewController = page
        self.window?.makeKeyAndVisible()
        return true
    }
}
class Page: UIViewController {



    override func viewDidLoad() {
        super.viewDidLoad()

        let myLabel = UILabel()
        let myString = "P is for Pizza and Pizza is for me"

        view.backgroundColor = UIColor.white
        //initialize the label to be the entire view
        //and to word wrap

        myLabel.frame = view.bounds.insetBy(dx: 20,dy: 20)
        //mylabel.frame.size.width = 350.0//uncomment for playgrounds
        myLabel.lineBreakMode = .byWordWrapping
        myLabel.numberOfLines = 0
//        myLabel.backgroundColor = UIColor.yellow
        myLabel.text = myString
        view.addSubview(myLabel)

        //: Initialize the mutable string
        let myMutableString = NSMutableAttributedString(
            string: myString,attributes: [NSFontAttributeName:
                UIFont(name: "Georgia",size: 18.0)!])

        // for first Pizza
        myMutableString.addAttribute(
            NSFontAttributeName,value: UIFont(
                name: "Chalkduster",size: 24.0)!,range: NSRange(
                location: 9,length: 5))

        //: Make a big blue P
        myMutableString.addAttribute(
            NSFontAttributeName,value: UIFont(
                name: "AmericanTypewriter-Bold",size: 36.0)!,range: NSRange(
                location:0,length:1))
        myMutableString.addAttribute(
            NSForegroundColorAttributeName,value: UIColor.blue,length:1))


        //: Make the second pizza red and outlined in Helvetica Neue
        myMutableString.addAttribute(
            NSFontAttributeName,value: UIFont(
                name: "Helvetica Neue",range: NSRange(
                location: 19,length: 5))

        myMutableString.addAttribute(
            NSStrokeColorAttributeName,value: UIColor.red,range:  NSRange(
                location: 19,length: 5))

        myMutableString.addAttribute(
            NSStrokeWidthAttributeName,value: 4,length: 5))

        //: Set the background color is attributes text.
        //: which is not the color of the background text.
        let  stringLength = myString.characters.count
        myMutableString.addAttribute(NSBackgroundColorAttributeName,value: UIColor.magenta,range: NSRange(
                                        location: 0,length: stringLength))



        //: Add a Drop Shadow

        //: Make the Drop Shadow
        let shadow = NSShadow()
        shadow.shadowOffset = CGSize(width: 5,height: 5)
        shadow.shadowBlurRadius = 5
        shadow.shadowColor = UIColor.gray

        //: Add a drop shadow to the text
        myMutableString.addAttribute(
            NSShadowAttributeName,value: shadow,range: NSRange(
                location: 27,length: 7))

        //:Change to 48 point Menlo
        myMutableString.addAttribute(
            NSFontAttributeName,value: UIFont(
                name: "Menlo",size: 48.0)!,length: 7))

        //: Appending the String with !!! and an Attributed String
        let myAddedStringAttributes:[String:AnyObject]? = [
            NSFontAttributeName:UIFont(
                name: "AvenirNext-Heavy",NSForegroundColorAttributeName:UIColor.red,NSShadowAttributeName: shadow

        ]
        let myAddedString = NSAttributedString(
            string: "!!!",attributes: myAddedStringAttributes)
        myMutableString.append(myAddedString)

        //: Apply to the label
        myLabel.attributedText = myMutableString

    }

}

相当的具有表现力。