如何遍历字符串并创建一个字典来计算该字符串中的字符数[重复]

Question

let input = "aa bb c"
let expected: [Character: Int] = [
            "a": 2,
            "b": 2,
            "c": 1,
        ]

这是我的代码。知道我可能做错了什么吗？

func createCounter(string: String) {
    var charArr: [Character] = []
    let mappedChar = charArr.map { ($0, 1)}
    let counts = Dictionary(mappedChar, uniquingKeysWith: +)
    
    for char in string {
        if (char != " ") {
            charArr.append(char)
        }
    }
    
    print(counts)
    
}

Answer 1

我发现我需要做的就是创建一个没有空格的新字符串，创建并清空字典并循环遍历新字符串。这是我的新代码。

    var newString: String = ""
    var countDict: [Character: Int] = [:]
    
    for char in string {
        if (char != " ") {
            newString.append(char)
        }
    }
    
    for char in newString {
        if (countDict[char] != nil) {
            countDict[char]! += 1
        } else {
            countDict[char] = 1
        }
    }
    
    print(countDict)
    
}