swift给定一个字符串，统计字符串中大小写字母、数字、空格及其他未识别类型字符个数

在Swift中，你可以使用`Scanner`或`Collections`框架来统计一个字符串中各个类型的字符数。这里是一个简单的示例：

import Foundation

func countCharactersInString(_ input: String) -> [CharacterCount: Int] {
    var characterCounts = ["lowercase": 0, "uppercase": 0, "digits": 0, "spaces": 0, "other": 0]
    
    let scanner = Scanner(string: input)
    while scanner.scanCharacters(from: .alphanumerics) {
        if Character.isLowercase(scanner.scanLocation == 0) {
            characterCounts["lowercase"] += 1
        } else if Character.isUppercase(scanner.scanLocation == 0) {
            characterCounts["uppercase"] += 1
        } else if scanner.string[scanner.location - 1].isNumber {
            characterCounts["digits"] += 1
        } else if scanner.string[scanner.location - 1] == " " {
            characterCounts["spaces"] += 1
        } else {
            characterCounts["other"] += 1
        }
        scanner.scanLocation++
    }
    
    return characterCounts
}

let inputString = "Hello World! 123"
let result = countCharactersInString(inputString)
print("Character counts:")
for (category, count) in result {
    print("\(category): \(count)")
}