Validate NSString for Hexadecimal value

Swift 5

extension String {
    var isHexNumber: Bool {
        filter(\.isHexDigit).count == count
    }
}

print("text1".isHexNumber) // false
print("aa32".isHexNumber) // true
print("AD1".isHexNumber) // true

Does this method work for you?

    NSString *string = @"FF";

    NSCharacterSet *chars = [[NSCharacterSet 
        characterSetWithCharactersInString:@"0123456789ABCDEF"] invertedSet];

    BOOL isValid = (NSNotFound == [string rangeOfCharacterFromSet:chars].location);