如何将数组中的每个字母与另一个数组中的所有字母进行比较？ - 斯威夫特

Question

我有 2 个不同的数组，称为：criptedChar 和字母表。我需要检查 criptedChar 中的第一个字符（所以“criptedchar [0]”）并检查字母表中的对应关系。 举个例子： criptedChar // ["d","e","c","b"] 字母表 // ["a","b","c" 等等] 我想从 criptedChar[0] 中取出 d 并检查所有字母表中是否有“d”，然后将“d”的位置保存在第二个数组中。 我还需要增加 criptedChar 括号内的数字。我会从用户那里获取号码。 你能帮我么？谢谢！

func decript() {
    var criptedText = incriptedText.text!   //get text from uiTextField
    var criptedChar = Array<Character>(criptedText.characters)  //from text to char & all in array :D
    var alfabeto: Array<Character> = ["a","b", "c", "d", "e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]
    var capacityCriptedCharArray = criptedChar.capacity

    for (var i = 0; i < 26; i++) {
        if criptedChar[0] == alfabeto[i] {
            decriptedText.text = decriptedText.text! + "\(newLettersFromSecondViewController[i])"
        }
    }


    for (var i = 0; i < 26; i++) {
        if criptedChar[1] == alfabeto[i] {
            decriptedText.text = decriptedText.text! + "\(newLettersFromSecondViewController[i])"
        }
    }

    for (var i = 0; i < 26; i++) {
        if criptedChar[2] == alfabeto[i] {
            decriptedText.text = decriptedText.text! + "\(newLettersFromSecondViewController[i])"
        }
    }   
}

此代码有效，但它很笨，我无法控制用户输入

Answer 1

如果我正确理解您的问题，您正在寻找 像这样的东西（内联解释）：

// Start with your crypted text, and an empty string for the result:
let cryptedText = "mifpyx"
var decryptedText = ""

// Two character arrays (of equal length):
let alphabet   = Array("abcdefghijklmnopqrstuvwxyz".characters)
let newLetters = Array("ghijklmnopqrstuvwxyzabcdef".characters)

// For each character in the input string:
for c in cryptedText.characters {
    // Check if `c` is contained in the `alphabet` array:
    if let index = alphabet.indexOf(c) {
        // Yes, it is, at position `index`!
        // Append corresponding character from second array to result:
        decryptedText.append(newLetters[index])
    }
}

print(decryptedText) // solved

或者，您可以从 两个数组：

var mapping = [ Character : Character ]()
zip(alphabet, newLetters).forEach {
    mapping[$0] = $1
}

然后将输入中的每个字符映射到那个 字典：

let decryptedText = Array(cryptedText.characters
        .map { mapping[$0] }
        .flatMap { $0 }
    )

（这里flatMap用于从输入数组中不存在的字符中过滤掉nils。）

Answer 2

以下是您可能可以适应您的应用程序的简单密码逻辑示例：

let readableText = "the quick brown fox jumped over the lazy dog"

// letters: letters in readable text that will be encoded
// cypher : corresponding encoded letters
//
// note: letters and cypher must have the same number of elements
let letters:[Character] = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]
let cypher:[Character]  = ["o","p","q","r","a","b","c","d","e","f","g","h","i","u","v","w","x","y","z","j","k","l","m","n","s","t"]

// build a mapping disctionary from readable to encoded
var encode:[Character:Character] = [:]
for (index, letter) in letters.enumerate() { encode[letter] = cypher[index] } 

// encrypt the readble text  gives: "jda xkeqg pyvmu bvn fkiwar vlay jda hots rvc"
let cryptedText = String(readableText.characters.map({ encode[$0] ?? $0 })) 


// build a mapping disctionary from encoded to readable
var decode:[Character:Character] = [:]
for (index, letter) in cypher.enumerate() { decode[letter] = letters[index] }

// decrypted the encrypted text  gives: "the quick brown fox jumped over the lazy dog"
let decryptedText = String(cryptedText.characters.map({ decode[$0] ?? $0 }))