Swift solution for is-subsequence challenge: https://leetcode.com/problems/is-subsequence

is-subsequence.swift

class Solution {
    func isSubsequence(_ s: String, _ t: String) -> Bool {
        let sub = Array(s.utf8)
        let string = Array(t.utf8)
        
        var subIndex: Int = 0
        var stringIndex: Int = 0
        
        while stringIndex < string.count, subIndex < sub.count {
            if string[stringIndex] == sub[subIndex] {
                subIndex += 1
            }
            stringIndex += 1
        }
        
        return subIndex == sub.count
    }
}