How to check validity of URL in Swift?

Question

Trying to make an app launch the default browser to a URL, but only if the URL entered is valid, otherwise it displays a message saying the URL is invalid.

How would

Answer 1

I found this one clean (In Swift):

func canOpenURL(string: String?) -> Bool {
    guard let urlString = string else {return false}
    guard let url = NSURL(string: urlString) else {return false}
    if !UIApplication.sharedApplication().canOpenURL(url) {return false}

    //
    let regEx = "((https|http)://)((\\w|-)+)(([.]|[/])((\\w|-)+))+"
    let predicate = NSPredicate(format:"SELF MATCHES %@", argumentArray:[regEx])
    return predicate.evaluateWithObject(string)
}

Usage:

if canOpenURL("abc") {
    print("valid url.")
} else {
    print("invalid url.")
}

===

for Swift 4.1:

func canOpenURL(_ string: String?) -> Bool {
    guard let urlString = string,
        let url = URL(string: urlString)
        else { return false }

    if !UIApplication.shared.canOpenURL(url) { return false }

    let regEx = "((https|http)://)((\\w|-)+)(([.]|[/])((\\w|-)+))+"
    let predicate = NSPredicate(format:"SELF MATCHES %@", argumentArray:[regEx])
    return predicate.evaluate(with: string)
}

// Usage
if canOpenURL("abc") {
    print("valid url.")
} else {
    print("invalid url.") // This line executes
}

if canOpenURL("https://www.google.com") {
    print("valid url.") // This line executes
} else {
    print("invalid url.")
}