This blog­post is a con­tin­u­a­tion of Part 1. Please make sure you read that also to get the con­text of why the iOS App Mea­sure­ment library needs updates for iOS 5.

Tonight we are releas­ing an iOS App Mea­sure­ment update that includes a large change for clients using the default Vis­i­tor ID method that pre­vi­ously set the Vis­i­tor ID to the device’s unique iden­ti­fier (UDID).  We also fixed a bug in the Best Prac­tices Plu­gin, sec­tion 1.6 of the imple­men­ta­tion guide, that was arti­fi­cially inflat­ing pageviews.

The pur­pose of this blog­post is to notify you about the changes so you can make informed deci­sions on when you choose to update to the lat­est iOS App Mea­sure­ment release and how these changes impact your mobile ana­lyt­ics and mobile opti­miza­tion initiatives.

How will the Best Prac­tices Plu­gin fix impact my data?

The plu­gin no longer counts app starts and app returns from back­ground as a blank pageview. This will cause your over­all pageview counts to more accu­rately rep­re­sent pageviews. If you have not cur­rently imple­mented the Best Prac­tices Plu­gin or if you were fil­ter­ing out the blank pageview hits, this fix will not impact your data.

How will the default vis­i­tor ID changes impact my data?

NOTE : The default vis­i­tor ID change will impact apps using the default vis­i­tor ID only, not apps where you over­ride the default and set your own vis­i­tor ID.

Let’s start with the bad…

Since the vis­i­tor ID is the key to so many reports and cor­re­la­tions within the data, the list of reports impacted is not triv­ial.  For this rea­son, I strongly rec­om­mend you care­fully con­sider the tim­ing of your app update around your busi­ness report­ing require­ments to min­i­mize this impact.

The net impact of this update is all vis­i­tors will appear as new vis­i­tors when they update to the app ver­sion con­tain­ing this change.  Since not all vis­i­tors update apps imme­di­ately, your vis­i­tor data will be impacted dur­ing the tran­si­tion time.

I rec­om­mend tying this update to a report­ing bound­ary that makes sense for your busi­ness, i.e. first of month/quarter/year.

I also strongly rec­om­mend build­ing into your app track­ing strat­egy a method by which you have a reg­is­tered login for your apps and set that as the vis­i­tor ID when known.  If you are able to suc­cess­fully iden­tify users in your apps by the same ID as other chan­nels, you will be able to tie that vis­i­tor together across devices. Also, since this change is chang­ing on iOS first, you should be think­ing about and prepar­ing for a sim­i­lar move by the Android plat­form in the future.

Now for the goooood stuff…

We’ve removed all depen­dence on UDID from our libraries. This com­plies with Apple’s dep­re­ca­tion notice for iOS 5.

More impor­tantly, the pre­vi­ous vis­i­tor ID is not per­sis­tent with the vis­i­tor. Mean­ing if the vis­i­tor gets a new device, like I recently upgraded from the iPhone 4 to the iPhone 4S, the vis­i­tor looks like a new unique vis­i­tor on that new device. Our goal is to track a vis­i­tor across devices. The new method will do just that. The default vis­i­tor ID gen­er­ated by the library will be saved in the user defaults of the app, which gets backed up and reused on the new device, some­thing not pos­si­ble in the pre­vi­ous method using UDID as the vis­i­tor ID.

Con­versely, this also solves prob­lems with resold devices being counted as an exist­ing vis­i­tor. Even when a device is wiped clean by the new device owner, the UDID does not change on that device; there­fore, the vis­i­tor ID remained the same in the old method.  The new default vis­i­tor ID method will gen­er­ate a vis­i­tor ID for the new device owner.

More Good Stuff

We’ve heard from many of you about your strug­gles with app imple­men­ta­tion debug­ging.  We’re lis­ten­ing and work­ing on solu­tions.  If you are inter­ested in par­tic­i­pat­ing in our upcom­ing betas, please reg­is­ter here.

A spe­cial thanks to Pete, Bran­don and Will on the engi­neer­ing team and Shawn in client care for their con­tri­bu­tions to this post.

Please com­ment below with your thoughts and ques­tions on this topic.  Look for­ward to hear­ing from you.


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Land For Sale UK
Land For Sale UK

Our goal is to track a visitor across devices. The new method will do just that.

Jorgen Sorensen
Jorgen Sorensen

@Chris - I believe you've already found out by your own research, but in case anyone else is looking for where to download the iOS AppMeasurement libraries (By the way, you need to have Admin rights), you're right, this will be helpful information to add to this article: Click the Admin menu at the top of your suite, select Admin Console > Code Manager, select to generate code for iOS(iPhone and iPad), select a Report Suite, click Generate Code (and acknowledge the warning), then go to the Component Files tab to download the "" file. You may have noticed, there's a file in the package called "Readme-Important-Change-to-VisitorID.html" that briefly explains how the libraries were changed in response to the announcement of this deprecation by Apple. It also links to Part1 of this series, as linked in the first paragraph above.


Thanks for the heads-up but .... where exactly is your iOS App Measurement library that this post refers to?