A lot of people have been sending me e-mail about the solution to a problem that was not very well documented to DAS Calc. Sending the same stock reply to these people helps them out, but that’s only for the people who have spent the time to send a support request. The rest are probably frustrated that they can’t solve the problem and either don’t purchase or regret their purchase of the full version of the app. If I could somehow notify the users of the solution as an alert in the app, everyone’s happy and I stop getting e-mails. This isn’t a unique solution, but I’ve wrapped it up for you to use. I call it Remote Alert, and you can find the code on GitHub.
It’s pretty simple to use. Import GPFRemoteAlert.[hm] into your project and replace the server address in kGPFRemoteAlertServer with your own address. Have your AppDelegate download alerts at launch (application:didFinishLaunchingWithOptions:). When you ship your app, put [[GPFRemoteAlert sharedRemoteAlert] displayAlertsForModule:@"UNIQUE_ID"]; in spots where you may want to have an alert in the future. I’d suggest one per UIView in viewDidLoad. If you ever want to display an alert, just add it to the XML file on your server and all your users will see it, without shipping an update to the AppStore.
I still need to add some more features, like only showing the alert once and limiting based on the device hardware, but it’s still very functional as-is. Right now, you can only limit based on version number of your app. I hope this helps someone else!