import Foundation
let pattern = #"""
^
(?=(?:(?![mM]{2}).)*[mM]{2}(?:(?![mM]{2}).)*$)
(?=(?:(?![dD]{2}).)*[dD]{2}(?:(?![dD]{2}).)*$)
(?=(?:(?![yY]{2}(?:[yY]{2})?).)*[yY]{2}(?:[yY]{2})?(?:(?![yY]{2}(?:[yY]{2})?).)*$)
(?:
(?:[mM]{2}|[dD]{2}|[yY]{2}(?:[yY]{2})?)
(?:[_-](?!$))?
){3}
$
"""#
let regex = try! NSRegularExpression(pattern: pattern, options: [.anchorsMatchLines, .allowCommentsAndWhitespace])
let testString = #"""
The expected result is that only combinations such as the following can test true:
dd-mm-yy
MM-DD_YYYY
yyyy_dd-MM
mmddyy
YYYYddMM
And not something like:
ddyyyyymmmmmmmmm
mmddyymm
ADDITIONAL no-checks:
mmmmmm
yyyymmmm
yydddd
YYYYddMM-
ddyyyy
yyyymm
yyyydd
"""#
let stringRange = NSRange(location: 0, length: testString.utf16.count)
let matches = regex.matches(in: testString, range: stringRange)
var result: [[String]] = []
for match in matches {
var groups: [String] = []
for rangeIndex in 1 ..< match.numberOfRanges {
let nsRange = match.range(at: rangeIndex)
guard !NSEqualRanges(nsRange, NSMakeRange(NSNotFound, 0)) else { continue }
let string = (testString as NSString).substring(with: nsRange)
groups.append(string)
}
if !groups.isEmpty {
result.append(groups)
}
}
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