URL validation in Swift

Question

In my Swift iOS project, I want to check whether is the valid url or not before requesting to server. I did earlier in Objective C code to check many elements like presence of www, http, https, :, etc to validate whether the right url or not. Do we have anything similar in Swift code?

I am expecting like this Obj C method.

 - (BOOL) validateUrl: (NSString *) candidate {
    NSString *urlRegEx =
    @"(http|https)://((\\w)*|([0-9]*)|([-|_])*)+([\\.|/]((\\w)*|([0-9]*)|([-|_])*))+";
    NSPredicate *urlTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", urlRegEx]; 
    return [urlTest evaluateWithObject:candidate];
}

Please suggest.

I tried to use NSPredicate predicateWithFormat, but couldn't be achieved in Swift. — Stella, Mar 17 '15 at 17:40
Hi, I need to validate for this URL -> h t t p://192.168.1.146:8081/Myservelet/WebserviceA/?username=stella — Stella, Mar 17 '15 at 18:32

score 10 · Answer 1 · answered Aug 13 '18 at 11:22

10

Swift 4.x

This Covers all types of validation like Subdomain, with or without HTTP / HTTPS

func isValidUrl(url: String) -> Bool {
    let urlRegEx = "^(https?://)?(www\\.)?([-a-z0-9]{1,63}\\.)*?[a-z0-9][-a-z0-9]{0,61}[a-z0-9]\\.[a-z]{2,6}(/[-\\w@\\+\\.~#\\?&/=%]*)?$"
    let urlTest = NSPredicate(format:"SELF MATCHES %@", urlRegEx)
    let result = urlTest.evaluate(with: url)
    return result
}

Hope this works for you.

answered Aug 13 '18 at 11:22

Ashu

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1

Tested this code with Swift 5, unfortunately `stackoverflow.com.com` returns `true`, while `129.0.0.1` and `ftp://129.0.0.1` return `false.` – Neph Jul 26 '19 at 09:15

Leo Dabus · Answer 2 · 2015-04-02T03:22:38.607

4

You can use the method stringByAddingPercentEscapesUsingEncoding to replace any special characters your link may have and then you can check if your link is a valid url using NSURL(string:) as follow:

let link =  "http://www.yourUrl.com".stringByRemovingPercentEncoding!.stringByAddingPercentEscapesUsingEncoding(NSUTF8StringEncoding)!

if let checkedUrl = NSURL(string: link) {
    // you can use checkedUrl here
}

Note: NSURL(string:) is only for weblinks. If you would like to create a NSURL for a local resource file you need to use NSURL(fileURLWithPath:)

edited Apr 02 '15 at 03:22

answered Mar 17 '15 at 17:42

Leo Dabus

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2

You probably want to explain the rationale – Wain Mar 17 '15 at 17:45
2

@Wain What's to explain? NSURL already does the checking and only returns an instance if a valid string was given to it. No need to reinvent the wheel. – Filip Radelic Mar 17 '15 at 17:50
I didn't say reinvent the wheel, just describe why it works, so basically your comment in the answer. +1 anyway but the explanation adds value. – Wain Mar 17 '15 at 20:30
1

This is an incorrect answer. See my full answer below. – Stefan Arentz Apr 02 '15 at 12:20

score 3 · Answer 3 · answered May 06 '16 at 06:34

3

Try this.

func validateUrl (urlString: String?) -> Bool {
    let urlRegEx = "(http|https)://((\\w)*|([0-9]*)|([-|_])*)+([\\.|/]((\\w)*|([0-9]*)|([-|_])*))+"
    return NSPredicate(format: "SELF MATCHES %@", urlRegEx).evaluateWithObject(urlString)
}

answered May 06 '16 at 06:34

swathy krishnan

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9
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score 3 · Answer 4 · answered Dec 07 '21 at 00:10

3

All the answers so far seem to involve regex, which seems potentially error prone (easy to miss something on our end). Another option is just creating the url object, and leaving the validation to the Foundation framework.

func validateURL(urlString: String) -> Bool {
    let url = URL(string: urlString)
    return url.host != nil && url.scheme != nil /* and whatever other checks you want */
}

If the URL couldn't be parsed, the host, scheme, etc. will be nil.

answered Dec 07 '21 at 00:10

Ryan

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Your answer did worked for me. Thanks :) – steveSarsawa Feb 16 '22 at 05:04
The scheme will not be nil even for abc://abc.com so this solution is not validating HTTP or https – Alok May 17 '23 at 09:34

score 2 · Answer 5 · answered Jan 10 '20 at 10:28

2

Swift 5

As none of the above solutions worked for me in Swift 5, I ended up writing my own REGEX for swift 5. This covers all types of validation including PORT

func validateURL(url: String) -> Bool {
        let regex = "http[s]?://(([^/:.[:space:]]+(.[^/:.[:space:]]+)*)|([0-9](.[0-9]{3})))(:[0-9]+)?((/[^?#[:space:]]+)([^#[:space:]]+)?(#.+)?)?"
        let test = NSPredicate(format:"SELF MATCHES %@", regex)
        let result = test.evaluate(with: url)
        return result
 }

answered Jan 10 '20 at 10:28

Vittal Pai

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25
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This indeed works with ports (e.g. `http://127.0.0.1:8080/test/test`) but only if the URL starts with "http" or "https" (it fails for e.g. `http://---`, which shouldn't be valid). It doesn't work with e.g. `stackoverflow.com` or `www.stackoverflow.com`, even though they are both valid. I tried to replace the beginning (`http[s]?://`) with `((http|https|ftp)://)?` but then even `---`is valid, while e.g. `127.0..0.1` isn't (which is correct). – Neph Apr 21 '23 at 11:24

score 2 · Answer 6 · answered Sep 03 '20 at 06:28

2

this simple extension make life easy

extension String {
    var isValidUrl: Bool {
        let urlRegEx = "((?:http|https)://)?(?:www\\.)?[\\w\\d\\-_]+\\.\\w{2,3}(\\.\\w{2})?(/(?<=/)(?:[\\w\\d\\-./_]+)?)?"
        return NSPredicate(format: "SELF MATCHES %@", urlRegEx).evaluate(with: self)
}

}

answered Sep 03 '20 at 06:28

Awais Mobeen

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This one fails: https://res.mycloud.com/thor.gif. But this regex is much better than others mentioned. – Kevv Keka Jul 08 '21 at 04:13

score 1 · Answer 7 · answered Apr 02 '15 at 03:01

I have a problem with the highest rated answer here. I think it is plain wrong for two reasons:

First, the stringByAddingPercentExcapedUsingEncoding will actually double encode valid URLs, thus making them invalid or at least different than the original input. If the input string is already a correctly encoded URL then you should just use that.

For example, http://foo.com/My%20Stuff/ will become http://foo.com/My%2520Stuff/ which is not the same. If you feed that to NSURL, it will actually decode it to a URL with a literal % in it.

Second, NSURL is known to be very bad at recognizing bad input. For example it happily returns an non-nil result when you give it something like x/3:()foo/blah which is clearly malformed and not a valid URL.

I think it is best to use a regular expression. I don't think there is anything in Foundation that can properly validate URLs.

score 1 · Answer 8 · answered Feb 07 '17 at 08:00

I've found that this is pretty easy to swift

func validateUrl() -> Bool {
  let urlRegEx = "((\\w)*|([0-9]*)|([-|_])*)+([\\.|/]((\\w)*|([0-9]*)|([-|_])*))+"
  return NSPredicate(format: "SELF MATCHES %@", urlRegEx).evaluate(with: self)
}

I find this easy. If you put as an extension or just in the class you can say

func fooBar(textField: UITextField) {   
   if textField == someTextField {
      if textField.text?.validateUrl() == true {
         print("true")
      } else {
         print("false")
      }
   }
}

Very similar to other answers tho, and years late

This doesn't require the http part, I feel like most users wouldn't bother typing in the http or https like http://www.google.com but instead just google.com or www.google.com

Obviously you could go the extra mile and check if they did or did not put the http(s) and if you really want to add it add it yourself..or not

score 1 · Answer 9 · answered Feb 26 '21 at 11:09

For Swift 5.0

func validateUrl (urlString: String?) -> Bool {
        let urlRegEx = "(http|https)://((\\w)*|([0-9]*)|([-|_])*)+([\\.|/]((\\w)*|([0-9]*)|([-|_])*))+"
        return NSPredicate(format: "SELF MATCHES %@", urlRegEx).evaluate(with: urlString)
    }

score 0 · Answer 10 · edited Mar 17 '15 at 17:46

0

I suggest using regular expression like this. The pattern below is correct for url.

let regex = NSRegularExpression(pattern: "/^(https?:\/\/)?([\da-z\.-]+)\.([a-z\.]{2,6})([\/\w \.-]*)*\/?$/",options: nil, error: nil)!

if regex.firstMatchInString(searchTerm!, options: nil, range: NSMakeRange(0, searchTerm!.length)) != nil {
    println("not valid url ")
}

edited Mar 17 '15 at 17:46

Wain

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answered Mar 17 '15 at 17:43

Christophe Maggi

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Is this compiling properly? It is not compiling this code. Build error in the 1st line - "Consecutive statements on a line must be seperated by ;" – Stella Mar 17 '15 at 17:50

score 0 · Answer 11 · answered Feb 07 '17 at 08:10

I have another solution. In Swift 3

import Foundation
import UIKit

extension String {

    var canOpenURL : Bool {

        guard let url = NSURL(string: self) else {return false}
        if !UIApplication.shared.canOpenURL(url as URL) {return false}
        let regEx = "((https|http)://)((\\w|-)+)(([.]|[/])((\\w|-)+))+"
        let predicate = NSPredicate(format:"SELF MATCHES %@", argumentArray:[regEx])
        return predicate.evaluate(with: self)
    }
}

It can be used as

if textField == someTextField {

    if (self.textField.text?.canOpenURL)! {
        //URL valid
    }else {
       //URL invalid
    }
}

score 0 · Answer 12 · answered Aug 25 '22 at 06:17

private var cancellbleSet: Set<AnyCancellable> = []

 func validateUrl1() {
    $url1
        .receive(on: RunLoop.main)
        .dropFirst()
        .sink { [self] in
            if $0 != "" {
                let pattern = "^(https?://)?(www\\.)?([-a-z0-9]{1,63}\\.)*?[a-z0-9][-a-z0-9]{0,61}[a-z0-9]\\.[a-z]{2,6}(/[-\\w@\\+\\.~#\\?&/=%]*)?$"
                let regex : Regex  = pattern.r!
                if regex.matches($0) {
                    isUrl1Valid = true
                } else {
                    isUrl1Valid = false
                }
            }
        }
        .store(in: &cancellbleSet)
}

Then you can call it inside the view model init, like this

 override init() {
    super.init()
    validateUrl1()
}

Lal Krishna · Answer 13 · 2018-01-24T08:53:01.640

-1

You could use Regex to validate URL Format

(https?://(www.)?)?[-a-zA-Z0-9@:%._+~#=]{2,256}.[a-z]{2,6}b([-a-zA-Z0-9@:%_+.~#?&//=]*)

SWIFT 4:

func validateURL (urlString: String) -> Bool {
    let urlRegEx = "(https?://(www.)?)?[-a-zA-Z0-9@:%._+~#=]{2,256}.[a-z]{2,6}b([-a-zA-Z0-9@:%_+.~#?&//=]*)"
    let urlTest = NSPredicate(format:"SELF MATCHES %@", urlRegEx)
    return urlTest.evaluate(with: urlString)
}

edited Jan 24 '18 at 08:53

answered Jan 18 '18 at 11:57

Lal Krishna

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URL validation in Swift

13 Answers13

Swift 5

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