@swift-4.2.4 @swift-5.0.3
import Foundation // column 1 2 3 4 5 6 7 8 9 10 11 // line 1 L I N E 1 _ 6 7 あ \n // line 2 L I N E 2 _ 7 8 9 0 \n // line 3 L I N E 3 _ 8 9 0 1 \n let string = "LINE1_67あ\nLINE2_7890\nLINE3_8901\n" let rangeOfFirstLine = string.lineRange(for: string.startIndex..<string.startIndex) let firstLine = string[rangeOfFirstLine] print(string.distance(from: rangeOfFirstLine.lowerBound, to: rangeOfFirstLine.upperBound)) print(firstLine == "LINE1_67あ\n")