如何在Swift中找出字母是字母数字还是数字

发布于07月01日

我想计算以下字符串中字母、数字和特殊字符的数量:

let phrase = "The final score was 32-31!"

我试过:

for tempChar in phrase {
    if (tempChar >= "a" && tempChar <= "z") {
       letterCounter++
    }
// etc.

但我有错误.我在这方面try 了各种各样的变化——仍然会出错——比如:

找不到"&lt；="的重载它接受提供的参数

推荐答案

Swift 5见rustylepord's answer.

Update for Swift 3:

let letters = CharacterSet.letters
let digits = CharacterSet.decimalDigits

var letterCount = 0
var digitCount = 0

for uni in phrase.unicodeScalars {
    if letters.contains(uni) {
        letterCount += 1
    } else if digits.contains(uni) {
        digitCount += 1
    }
}

(Previous answer for older Swift versions)

一个可能的快速解决方案:

var letterCounter = 0
var digitCount = 0
let phrase = "The final score was 32-31!"
for tempChar in phrase.unicodeScalars {
    if tempChar.isAlpha() {
        letterCounter++
    } else if tempChar.isDigit() {
        digitCount++
    }
}

Update:上述解决方案仅适用于ASCII字符集中的字符，

let letters = NSCharacterSet.letterCharacterSet()
let digits = NSCharacterSet.decimalDigitCharacterSet()

var letterCount = 0
var digitCount = 0

for uni in phrase.unicodeScalars {
    if letters.longCharacterIsMember(uni.value) {
        letterCount++
    } else if digits.longCharacterIsMember(uni.value) {
        digitCount++
    }
}

Update 2:从Xcode 6 beta 4开始，第一个解决方案不再有效，因为