Percent encode a URL String

String+RFC3986.swift

import Foundation

extension String {
    public func addingPercentEncodingForRFC3986() -> String? {
        let unreserved = "-._~/?"
        let allowed = NSMutableCharacterSet.alphanumeric()
        allowed.addCharacters(in: unreserved)
        return self.addingPercentEncoding(withAllowedCharacters: allowed as CharacterSet)
    }
    
    public func addingPercentEncodingForFormData(plusForSpace: Bool=false) -> String? {
        let unreserved = "*-._"
        let allowed = NSMutableCharacterSet.alphanumeric()
        allowed.addCharacters(in: unreserved)

        if plusForSpace {
            allowed.addCharacters(in: " ")
        }

        var encoded = self.addingPercentEncoding(withAllowedCharacters: allowed as CharacterSet)
        
        if plusForSpace {
            encoded = encoded?.replacingOccurrences(of: " ", with: "+")
        }
        return encoded
    }
}

Shamelessly ripped off from: https://useyourloaf.com/blog/how-to-percent-encode-a-url-string/