Avoiding delays on the UI thread in iOS is key to ensure a snappy interface. Long running should be queued in operation queues to make sure they don't impact perceived performance.
Adding in functionality to an existing class in Cocoa is easy using categories. This can be useful for methods that should be transient or when access to the original code is restricted.
Over the past year Apple has released an amazing set of phones and tablets. While the devices are incredible the framework and language have a few shortcomings that Apple will have to address.
