WhatsApp Swift UIActivityViewController Custom UIActivity

UIActivity WhatsApp

How to add WhatsApp to UIActivityViewController?

Drop the Whatsapp.swift file in your project.
Initialize the controller as described in ViewController.swift

ViewController.swift

//HOW TO USE THE WHATSAPP SHARE ACTION

    @IBAction func shareAction(sender: UIButton) {
        let objectsToShare = [message]
        let wsActivity = WhatsAppActivity()
        let activityVC = UIActivityViewController(activityItems: objectsToShare, applicationActivities: [wsActivity])
        activityVC.excludedActivityTypes = [UIActivityTypeAirDrop, UIActivityTypeAddToReadingList,UIActivityTypeCopyToPasteboard,UIActivityTypeSaveToCameraRoll,UIActivityTypePrint]
        
        self.presentViewController(activityVC, animated: true, completion: nil)
    }

Whatsapp.swift

//
//  Whatsapp.swift
//  Send2Phone
//
//  Created by Sohel Siddique on 3/27/15.
//  Copyright (c) 2015 Zuzis. All rights reserved.
//

import UIKit

class WhatsAppActivity : UIActivity{
    
    override init() {
        self.text = ""
        
    }
    
    var text:String?

    
    override func activityType()-> String {
        return NSStringFromClass(self.classForCoder)
    }
    
    override func activityImage()-> UIImage
    {
        return UIImage(named: "whatsapp2")!;
    }
    
    override func activityTitle() -> String
    {
        return "WhatsApp";
    }
    
    override class func activityCategory() -> UIActivityCategory{
        return UIActivityCategory.Share
    }

    func getURLFromMessage(message:String)-> NSURL
    {
        var url = "whatsapp://"
    
        if (message != "")
        {
            url = "\(url)send?text=\(message)"
        }
    
        return NSURL(string: url)!
    }
    
    override func canPerformWithActivityItems(activityItems: [AnyObject]) -> Bool {
        for activityItem in activityItems
        {
            if (activityItem.isKindOfClass(NSString))
            {
                self.text = activityItem as? String;
                var whatsAppURL:NSURL  = self.getURLFromMessage(self.text!)
                return UIApplication.sharedApplication().canOpenURL(whatsAppURL)
            }
        }
        return false;
    }
    
    override func prepareWithActivityItems(activityItems: [AnyObject]) {
        for activityItem in activityItems{
            if(activityItem.isKindOfClass(NSString)){
                var whatsAppUrl:NSURL = self.getURLFromMessage(self.text!)
                if(UIApplication.sharedApplication().canOpenURL(whatsAppUrl)){
                    UIApplication.sharedApplication().openURL(whatsAppUrl)
                }
                break;
            }
        }
    }
}

@artur that could be cuz of two reasons. Either the simulator does not contain whatsapp, or your code is not passing the expected message to the whatsapp share extension

Or that your canOpenUrl function is not working for which you would have to add this to you info.plist file:
"<''key''>LSApplicationQueriesSchemes<''/key>
<''array>
<''string>whatsapp<''/string>
<''/array>
<''/dict>"

Hi, Sir,
I found few app now can share both image + text, do you have any idea how to implement. I can do only image (by UIdocumentInteractionController) or only text. Appreciate if you can teach me how to share photo + text to whatsapp.
Thanks in advanced.

This is not how it's supposed to be done. You should only store the URL in prepareWithActivityItems and open it in performActivity.
See the docs on prepareWithActivityItems:

Subclasses should override this method and use it to store a reference to the data items in the activityItems parameter.

https://developer.apple.com/reference/uikit/uiactivity/1620668-preparewithactivityitems

its not working for swift 4