Swift: Repeating letters turn to a number in a String [closed]

Answer 1

Let's start with this string :

let abc : String = "aaaabbbbbbbccffffde"

And have the output in a new variable

var result = ""

Let's use an index to go through the characters in the string

var index = abc.startIndex

while index < abc.endIndex {
    //There is already one character :
    let char = abc[index]
    var count = 0

    //Let's check the following characters, if any
    repeat {
        count += 1
        index = abc.index(after: index)
    } while index < abc.endIndex && abc[index] == char

    //and update the result accordingly 
    result += count < 3 ?
        String(repeating: char, count: count) :
        String(char) + String(count)
}

And here is the result :

print(result)  //a4b7ccd3e