Stride String

String.stride.swift

extension String {
    func stride(by distance: String.IndexDistance, substring: (String.SubSequence) -> Void) {
        guard distance > 0, distance < count else {
            substring(self[...])
            return
        }
        
        var i = index(startIndex, offsetBy: distance, limitedBy: endIndex) ?? endIndex
        var previ = startIndex
        while i < endIndex {
            substring(self[previ..<i])
            previ = i
            i = index(i, offsetBy: distance, limitedBy: endIndex) ?? endIndex
        }
        
        substring(self[previ..<i])
    }
}