import Foundation
let pattern = #"(?<!^)\b[0-9]{5,9}:"#
let regex = try! NSRegularExpression(pattern: pattern, options: .anchorsMatchLines)
let testString = #"13371337:Bat,TH,Li-Met,Blub,9.5V,370mAHr,1/2_AA-Cell,50pcs,13351234:Radio - Antenna 2.4 GHz AB/C midi (10p),15642345:Board SMB - Some Magic Board,95653345:Board SMK 6 - Some Magic Knobs - Mod6,56735632:Control Unit Z65 - Mod9"#
let stringRange = NSRange(location: 0, length: testString.utf16.count)
let substitutionString = #"\n\g<0>"#
let result = regex.stringByReplacingMatches(in: testString, range: stringRange, withTemplate: substitutionString)
print(result)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Swift 5.2, please visit: https://developer.apple.com/documentation/foundation/nsregularexpression