Hi @oscara95388635,
If I have correctly understand you meant tracking for webview of web pages is working fine implemented via Adobe Launch however for App tracking on iPad App, evar returns unspecified in reports.
In case of App Tracking, evars cannot be configured directly in the server call, you would first need to setup a context data variable wherein you will be passing values for desired evar and then map that context data variables with an evar via Processing Rules.