The iPhone OS started off with a single device, the original iPhone, ala, iPhone 1,1. In the last three years, Apple has been innovating hard and introduced multiple devices running the same operating system with different capabilities. For example, the original iPod touch, iPod 1,1 wasn’t able to record audio input, and till date iPod Touch cannot vibrate as a result of an alert. There are many such subtle differences between...

In iOS 4, Apple introduced a new way to send “push notifications” to your app without having a dedicated server and associated server side coding. The technique is called as scheduling local notifications. While this tutorial is about how to schedule local notifications, I would also explain how a powerful abstraction concept, Singleton design pattern could make this easier when adding local notification support to your app. If...

Update: An updated version for XCode 4  is available. Please check it out here. I have a habit of creating Singleton pattern classes for nearly every application I write. I manage the Settings Bundle (or any app settings, thru a Singleton class), my MKStoreManager for doing in-app purchases is a Singleton class. Even in Apple’s own code you can see some Singletons like UIApplication, Reachability (from the Reachability example),...

The following photo was taken using my hi-res super macro camera, Canon S5 IS. A quick comparison in the displays of iPad, iPhone 4 and Nexus One. The iPhone 4 display is clearly superior. You can download a higher resolution version of this image by right clicking the above image and clicking “Save link as…” Be forewarned, most low end computers can’t even open that image (as on the date of writing this). The...