Opens a deep link into an app (Waitress). If that app isn't installed, open the app store for the app instead. Encode a back link into the app open url so the target app can navigate back to this app.

openDeepLink.swift

//
//  ViewController.swift
//  ios-mall-demo
//
//  Created by Alexander Yngling on 26/10/15.
//  Copyright © 2015 Waitress AB. All rights reserved.
//

import UIKit

class PlaceIdPickerVC: UIViewController {

  
  @IBAction func onTapBtn(sender: UIButton) {
    guard let placeId = sender.titleLabel?.text else { return }
    openPlaceInWaitress(placeId)
  }

  
  func openPlaceInWaitress(placeId: String) {
    let backLinkString = "mall://home?id=10&f=1" // replace with whatever back link is needed
    
    let safeCharacterSet = NSCharacterSet.URLQueryAllowedCharacterSet().mutableCopy()
    safeCharacterSet.removeCharactersInString("&=?:/")
    let backLink = backLinkString.stringByAddingPercentEncodingWithAllowedCharacters(safeCharacterSet as! NSCharacterSet)!
    let url = NSURL(string:"waitress://www.waitress.com/places/\(placeId)?back=\(backLink)")!
    let app = UIApplication.sharedApplication()
    
    // Open the target URL
    if (app.canOpenURL(url)) {
      print("Can open url: \(url)")
      app.openURL(url);
      
      // Open the app store (the target app isn't installed)
    } else {
      UIPasteboard(name: "Waitress", create: true)?.string = "\(url)"
      print("Can't open url, added to pasteboard: \(url)")
      let appStore = NSURL(string:"itms://itunes.apple.com/app/apple-store/id874437345")! // http://stackoverflow.com/questions/433907/how-to-link-to-apps-on-the-app-store#comment2426466_2337601
      print("Opening appstore: \(appStore)")
      app.openURL(appStore)
    }
    
  }
  
}