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Xcode – Use regular expression in Swift String.contains() func

In Swift, I have a String Variable thisString. I want to check to make sure the string contains only letters, numbers and/or dashes (-). Aside from doing this:

if ( thisString.contains("$") || thisString.contains("%") ) {
  //reject
} else {
 //accept
}

for each undesired character, which is ridiculous, I cant figure it out..

I would like to, in theory, do something like this with a regular expression:

if ( thisString.contains(regex([^a-zA-Z0-9-]) ) { 
  //reject
} else {
  //accept
}

Is this possible?

Thank you!

Tags:

3

Answers


  1. 0

    Use NSPredicate with String extension.

    extension String {
    enum ValidationType: String {
        case alphabet = "[A-Za-z]+"
        case alphabetWithSpace = "[A-Za-z ]*"
        case alphabetNum = "[A-Za-z-0-9]*"
        case alphabetNumWithDash = "[A-Za-z-0-9-]*"
    }
    
    func isValid(_ type: ValidationType) -> Bool {
        guard !isEmpty else { return false }
        let regTest = NSPredicate(format: "SELF MATCHES %@", type.rawValue)
        return regTest.evaluate(with: self)
    }
}

    Usage

    thisString.isValid(.alphabetNumWithDash)
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  2. 0

    You are quite close

    if thisString.range(of: "[^a-zA-Z0-9-]", options: .regularExpression) != nil { 
  //reject
} else {
  //accept
}
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  3. 0

    You can create a set of characters and check if it is a superset of your string. It is much faster than using regex.

    let validCharacters: Set = .init("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-")

let string1 = "Lkabo-1"
let string2 = "Lkabo-2!"

if validCharacters.isSuperset(of: string1) {
    print(true)  // true
} else {
    print(false)
}
if validCharacters.isSuperset(of: string2) {
    print(true)
} else {
    print(false)  // false
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