Swift 3 String to URLRequest extension

StringExtension.swift

extension String{
    
    func asURLRequest()->URLRequest?{
        var urlRequest:URLRequest?
        if self.isValidForUrl(){
            if let url = URL(string: self){
                urlRequest = URLRequest(url: url)
            }
        }else{
            urlRequest = nil
        }
        return urlRequest
    }
    func isValidForUrl() -> Bool {
        
        if(self.hasPrefix("http") || self.hasPrefix("https")) {
            return true
        }
        return false
    }
}