Swift iOS : attributedText 富文本操作

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,
range: NSRange(
location:0,
length:1))

//: Make the second pizza red and outlined in Helvetica Neue
myMutableString.addAttribute(
NSFontAttributeName,
value: UIFont(
name: "Helvetica Neue",
size: 36.0)!,
range: NSRange(
location: 19,
length: 5))

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

myMutableString.addAttribute(
NSStrokeWidthAttributeName,
value: 4,
range: NSRange(
location: 19,
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)!,
range: NSRange(
location: 27,
length: 7))

//: Appending the String with !!! and an Attributed String
let myAddedStringAttributes:[String:AnyObject]? = [
NSFontAttributeName:UIFont(
name: "AvenirNext-Heavy",
size: 48.0)!,
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。