[Swift] 크기가 작은 부분 문자열

import Foundation

func solution(_ t:String, _ p:String) -> Int {
    var index = 0
    var result = [String]()
    
    var t = Array(t).map { String($0)}
    
    
    
    while index + p.count <= t.count {
        result.append(t[index..<index+p.count].joined())
        index += 1
    }
    
    return result.filter {$0 <= p}.count
}