Regular expression to get URL in string swift with Capitalized symbols - ios

Question

I try to get URLs in text. So, before, I used such an expression:
let re = NSRegularExpression(pattern: "https?:\\/.*", options: nil, error: nil)!
But I had a problem when a user input URLs with Capitalized symbols (like Http://Google.com, it doesn't match it).
I tried:
let re = NSRegularExpression(pattern: "(h|H)(t|T)(t|T)(p|P)s?:\\/.*", options: nil, error: nil)!
But nothing happened.

Answer 1

You turn off case sensitivity using an i inline flag in regex, see Foundation Framework Reference for more information on available regex features.
(?ismwx-ismwx)
Flag settings. Change the flag settings. Changes apply to the portion of the pattern following the setting. For example, (?i) changes to a case insensitive match.The flags are defined in Flag Options.
For readers:
Matching an URL inside larger texts is already a solved problem, but for this case, a simple regex like
(?i)https?://(?:www\\.)?\\S+(?:/|\\b)
will do as OP requires to match only the URLs that start with http or https or HTTPs, etc.

Answer 2

Swift 4
1. Create String extension
import Foundation
extension String {
var isValidURL: Bool {
guard !contains("..") else { return false }
let head = "((http|https)://)?([(w|W)]{3}+\\.)?"
let tail = "\\.+[A-Za-z]{2,3}+(\\.)?+(/(.)*)?"
let urlRegEx = head+"+(.)+"+tail
let urlTest = NSPredicate(format:"SELF MATCHES %#", urlRegEx)
return urlTest.evaluate(with: trimmingCharacters(in: .whitespaces))
}
}
2. Usage
"www.google.com".isValidURL

Answer 3

Try this - http?://([-\w\.]+)+(:\d+)?(/([\w/_\.]*(\?\S+)?)?)?
let pattern = "http?://([-\\w\\.]+)+(:\\d+)?(/([\\w/_\\.]*(\\?\\S+)?)?)?"
var matches = [String]()
do {
let regex = try NSRegularExpression(pattern: pattern, options: NSRegularExpressionOptions(rawValue: 0))
let nsstr = text as NSString
let all = NSRange(location: 0, length: nsstr.length)
regex.enumerateMatchesInString(text, options: NSMatchingOptions.init(rawValue: 0), range: all, usingBlock: { (result, flags, _) in
matches.append(nsstr.substringWithRange(result!.range))
})
} catch {
return [String]()
}
return matches

Answer 4

Make an exension of string
extension String {
var isAlphanumeric: Bool {
return rangeOfString( "^[wW]{3}+.[a-zA-Z]{3,}+.[a-z]{2,}", options: .RegularExpressionSearch) != nil
}
}
call using like this
"www.testsite.edu".isAlphanumeric // true
"flsd.testsite.com".isAlphanumeric //false

Answer 5

My complex solution for Swift 5.x
ViewController:
private func loadUrl(_ urlString: String) {
guard let url = URL(string: urlString) else { return }
let request = URLRequest(url: url)
webView.load(request)
}
UISearchBarDelegate:
func searchBarSearchButtonClicked(_ searchBar: UISearchBar) {
guard let text = searchBar.text else { return }
if !text.isUrl() {
let finalUrl = String(format: "%#%#", "https://www.google.com/search?q=", text)
loadUrl(finalUrl)
return
}
if text.starts(with: "https://") || text.starts(with: "http://") {
loadUrl(text)
return
}
let finalUrl = String(format: "%#%#", "https://", text)
loadUrl(finalUrl)
}
String extension:
extension String {
func isUrl() -> Bool {
guard !contains("..") else { return false }
let regex = "((http|https)://)?([(w|W)]{3}+\\.)?+(.)+\\.+[A-Za-z]{2,3}+(\\.)?+(/(.)*)?"
let urlTest = NSPredicate(format:"SELF MATCHES %#", regex)
return urlTest.evaluate(with: trimmingCharacters(in: .whitespaces))
}
}