Data Collection

3 Posts authored by: David Everly

One of the more significant new features included in Apple's iOS 5 release is iCloud. iCloud is your "hard drive in the sky" that keeps your devices in sync, and also serves as a backup mechanism.  Each user is given 5GB of free storage, with additional storage available for purchase.


As part of the iCloud rollout, Apple has issued new storage guidelines for developers.  These guidelines state that only user-generated data should be stored in the <Application_Home>/Documents folder.  This data is automatically backed up to iCloud and goes against the 5GB cap.  If an app stores too much data in this folder (as deemed by Apple), then it can be rejected from the App Store.


The Webtrends iOS Mobile SDK had been storing event data in Documents folder.  In our latest release ( we changed over to use <Application_Home>/Library/Caches folder instead.  If any event data exists in the Documents folder during an app upgrade, the SDK will automatically move it to the Library/Caches folder as well.  We recommend that you update your apps to use the latest release of the SDK as soon as possible. 




iOS Data Storage Guidelines (login required)


iOS Developer Library - File System Basics


In August 2011 TechCrunch reported that Apple will be phasing out access to the unique device identifier or UDID on iOS devices such as iPhones and iPads.  The Apple developer documentation cited in the report mentioned that UDID has been "deprecated in iOS 5".  This caused some concern in the mobile analytics community because vendors commonly use the UDID to identify visitors.


We believe that this is an early warning from Apple to give developers time to come up with alternatives.  We believe the feature will be marked as deprecated in iOS 5 but will still be available for use for a reasonable amount of time.  This phased approach to deprecation would be consistent with Apple's documentation on deprecated API usage, and also consistent with Apple's approach historically.


Webtrends Visitor Id

The first time a Webtrends-enabled app is run, a visitor id is established and written to application-specific persistent storage.  Thereafter the app uses the stored visitor id.  By default the Webtrends SDK for iOS uses a hashed version of the UDID for the visitor id.  You can already configure the Webtrends SDK for iOS to use a randomly generated value for the visitor id instead of the UDID.  This is done by adding the following lines to the Webtrends.plist file:



After making this configuration change, the updated app should be posted to the App Store.  Users who download the new version will then be tracked using the random vistor id.



In light of this announcement from Apple, Webtrends will modify its Mobile SDK for iOS.  The new version of the SDK will default to the randomly generated visitor id.  Until then, customers can achieve this result by using the above mentioned configuration setting.



  • Apple Sneaks A Big Change Into iOS 5: Phasing Out Developer Access To The UDID

  • Using SDK-Based Development - Deprecated API Usage

Windows Phone 7 Mobile SDK 1.0 Released


We are pleased to announce the availability of our Windows Phone 7 Mobile SDK.  The SDK is functionally equivalent to our other Mobile SDK offerings.  The SDK is comprised of a component DLL and a configuration file that you add to your Visual Studio project.  The SDK can be used in either Silverlight or XNA applications on Windows Phone 7.


We strive to make the process of adding analytics to your mobile application a simple task.  Let us know how we did by sending an email to


SDK Documentation:


SDK Download:

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