UILabelをNSAttributedStringで文字装飾（Swift 4対応）

let stringAttributes: [NSAttributedStringKey : Any] = [
    .foregroundColor : UIColor.blue,
    .font : UIFont.systemFont(ofSize: 24.0)
]
let string = NSAttributedString(string: "BlueString", attributes:stringAttributes)
label.attributedText = string

let stringAttributes1: [NSAttributedStringKey : Any] = [
    .foregroundColor : UIColor.blue,
    .font : UIFont.systemFont(ofSize: 24.0)
]
let string1 = NSAttributedString(string: "0123", attributes: stringAttributes1)

let stringAttributes2: [NSAttributedStringKey : Any] = [
    .foregroundColor : UIColor.red,
    .font : UIFont.boldSystemFont(ofSize: 20.0)
]
let string2 = NSAttributedString(string: "456", attributes: stringAttributes2)

let stringAttributes3: [NSAttributedStringKey : Any] = [
    .foregroundColor : UIColor.green,
    .font : UIFont.systemFont(ofSize: 16.0)
]
let string3 = NSAttributedString(string: "789", attributes:stringAttributes3)

let mutableAttributedString = NSMutableAttributedString()
mutableAttributedString.append(string1)
mutableAttributedString.append(string2)
mutableAttributedString.append(string3)

label.attributedText = mutableAttributedString;