快速String范围和NSString范围不是“兼容的”。例如，像😄这样的表情符号算作一个Swift字符，但算作两个NSString
字符（所谓的UTF-16代理对）。

因此，如果字符串包含此类字符，则建议的解决方案将产生意外结果。例：

let text = "😄😄😄Long paragraph saying!"
let textRange = text.startIndex..<text.endIndex
let attributedString = NSMutableAttributedString(string: text)

text.enumerateSubstringsInRange(textRange, options: NSStringEnumerationOptions.ByWords, { (substring, substringRange, enclosingRange, stop) -> () in
    let start = distance(text.startIndex, substringRange.startIndex)
    let length = distance(substringRange.startIndex, substringRange.endIndex)
    let range = NSMakeRange(start, length)

    if (substring == "saying") {
        attributedString.addAttribute(NSForegroundColorAttributeName, value: NSColor.redColor(), range: range)
    }
})
println(attributedString)

输出：

para长paragra {
} ph说{
    NSColor =“ NSCalibratedRGBColorSpace 1 0 0 1”;
} ing！{
}

如您所见，“ ph say”已被标记为属性，而不是“ saying”。

由于NS(Mutable)AttributedString最终需要使用NSStringand和an
NSRange，因此最好将给定的字符串转换为NSStringfirst。然后substringRange
是NSRange，则您不再需要转换范围：

let text = "😄😄😄Long paragraph saying!"
let nsText = text as NSString
let textRange = NSMakeRange(0, nsText.length)
let attributedString = NSMutableAttributedString(string: nsText)

nsText.enumerateSubstringsInRange(textRange, options: NSStringEnumerationOptions.ByWords, { (substring, substringRange, enclosingRange, stop) -> () in

    if (substring == "saying") {
        attributedString.addAttribute(NSForegroundColorAttributeName, value: NSColor.redColor(), range: substringRange)
    }
})
println(attributedString)

输出：

paragraph长款{
}说{
    NSColor =“ NSCalibratedRGBColorSpace 1 0 0 1”;
}！{
}

Swift 2更新：

let text = "😄😄😄Long paragraph saying!"
let nsText = text as NSString
let textRange = NSMakeRange(0, nsText.length)
let attributedString = NSMutableAttributedString(string: text)

nsText.enumerateSubstringsInRange(textRange, options: .ByWords, usingBlock: {
    (substring, substringRange, _, _) in

    if (substring == "saying") {
        attributedString.addAttribute(NSForegroundColorAttributeName, value: NSColor.redColor(), range: substringRange)
    }
})
print(attributedString)

Swift 3更新：

let text = "😄😄😄Long paragraph saying!"
let nsText = text as NSString
let textRange = NSMakeRange(0, nsText.length)
let attributedString = NSMutableAttributedString(string: text)

nsText.enumerateSubstrings(in: textRange, options: .byWords, using: {
    (substring, substringRange, _, _) in

    if (substring == "saying") {
        attributedString.addAttribute(NSForegroundColorAttributeName, value: NSColor.red, range: substringRange)
    }
})
print(attributedString)

Swift 4更新：

从Swift 4（Xcode
9）开始，Swift标准库提供了在Range<String.Index>和之间进行转换的方法NSRange。NSString不再需要转换为：

let text = "😄😄😄Long paragraph saying!"
let attributedString = NSMutableAttributedString(string: text)

text.enumerateSubstrings(in: text.startIndex..<text.endIndex, options: .byWords) {
    (substring, substringRange, _, _) in
    if substring == "saying" {
        attributedString.addAttribute(.foregroundColor, value: NSColor.red,
                                      range: NSRange(substringRange, in: text))
    }
}
print(attributedString)

这substringRange是一个Range<String.Index>，并将其转换为NSRange与

NSRange(substringRange, in: text)