Tutorial: Force Upgrade in Swift

Sometimes you need all users to use the same version of your App. There are many reasons for this but the most popular is to ensure all users have a specific new feature that’s only available in the latest version. Another popular reason is you changed a data source or functionality that is no longer supported in older versions of your app. This will force the user to upgrade the app on their device and will not allow them to use their current version anymore.

It’s important that this feature is built into your very first release of your application (v1.0) so you can force all users to upgrade when you need to.

Below is a tutorial to help you add a forced upgrade alert in Swift.

Web Server API

1. Create “appVersion.php” on your Server. This can be created using any kind of Web API (Perl, PHP, Ruby, etc..).
2. Write this code into your file. This code will give out your latest App Version.

   <php
    
       echo "1.1";
    
   ?>
   

Get App Version using NSURLConnection

1. You’ll need the following method to read in the latest App Version from the Web Server API.

   func getAppVersion() {
       let url = NSURL(string:"http://www.brianjcoleman.com/code/appVersion.php")
       let cachePolicy = NSURLRequestCachePolicy.ReloadIgnoringLocalCacheData
       var request = NSMutableURLRequest(URL: url!, cachePolicy: cachePolicy, timeoutInterval: 2.0)
       request.HTTPMethod = "POST"
       
       // set Content-Type in HTTP header
       let boundaryConstant = "----------V2ymHFg03esomerandomstuffhbqgZCaKO6jy";
       let contentType = "multipart/form-data; boundary=" + boundaryConstant
       NSURLProtocol.setProperty(contentType, forKey: "Content-Type", inRequest: request)
       
       // set data
       var dataString = ""
       let requestBodyData = (dataString as NSString).dataUsingEncoding(NSUTF8StringEncoding)
       request.HTTPBody = requestBodyData
       //println("Data String: \(dataString)")
       // set content length
       //NSURLProtocol.setProperty(requestBodyData.length, forKey: "Content-Length", inRequest: request)
       
       var response: NSURLResponse? = nil
       var error: NSError? = nil
       let reply = NSURLConnection.sendSynchronousRequest(request, returningResponse:&response, error:&error)
       
       let results = NSString(data:reply!, encoding:NSUTF8StringEncoding)
       println("API Response: \(results)")
       self.serverAppVersion = results!
   }
   

Display UIAlertController in Swift

1. Then you need to compare the minimum app version from the web server against the app version the user has on their device.
2. If the minimum app version from the server is greater than the users app version it will display an alert view and force the user to upgrade.
3. Add the method below into your first view controller in your app.

   func checkForAppUpdate() {
       
       getAppVersion()
       
       var minAppVersion = self.serverAppVersion
       var appVersion = NSBundle.mainBundle().objectForInfoDictionaryKey("CFBundleShortVersionString") as String
       
       println("Current Version: \(appVersion) -- Minimum Version: \(minAppVersion)")
       
       //Compare App Versions
       var minAppVersionComponents : NSArray = minAppVersion.componentsSeparatedByString(".")
       var appVersionComponents : NSArray = appVersion.componentsSeparatedByString(".")
       
       var needToUpdate = false
       
       for i in 0..<min(minAppVersionComponents.count, appVersionComponents.count)
       {
           var minAppVersionComponent = minAppVersionComponents.objectAtIndex(i) as String
           var appVersionComponent = appVersionComponents.objectAtIndex(i) as String
           
           var minApp: String = minAppVersionComponent
           var appVer: String = appVersionComponent
           
           if (minApp != appVer)
           {
               needToUpdate = (appVer < minApp)
               break;
           }
       }
       
       if (needToUpdate)
       {
           var alert = UIAlertController(title: "New Version Available", message: "There is a newer version available for download! Please update the app by visiting the Apple Store.", preferredStyle: UIAlertControllerStyle.Alert)
           alert.addAction(UIAlertAction(title: "Update", style: UIAlertActionStyle.Default, handler: { alertAction in
               UIApplication.sharedApplication().openURL(NSURL(string : "https://itunes.apple.com/app/cheapo-casino-free-casino/id637522371?ls=1&mt=8")!)
               alert.dismissViewControllerAnimated(true, completion: nil)
               }))
           self.presentViewController(alert, animated: true, completion: nil)
       }
       
   }
   

4. Lastly you’ll need to call the checkForAppUpdate() from viewDidLoad() so it will only get called the when the app is initially loaded.

You can grab the full source code for this tutorial. Note: Built using XCode6.1
If you need it built using Xcode 6.3 (Swift 1.2).

Jul 31, 2014 Brian Coleman