In Mac OS X 10.6 and iOS 4, Apple added blocks to Objective-C. When I first started looking at them because various APIs used them, the syntax confused me, and I pretty much ignored them as I was still doing work that ran on iOS 4 and Mac OS X 10.5.
This spring, all my projects moved to iOS 4 and Mac OS X 10.6 as the minimum requirements, so I took another pass at learning blocks. This time, however, I could actually use them and read all I could about them. The more I started looking at them, the more I became enamored with them. I started using blocks in my own APIs and just finished rewriting a significant chunk of code using blocks. Using blocks has made my code more readable and has greatly simplified certain aspects of our app.
One of my co-workers cautioned me to not use blocks just because they were the shiny new tool which I admit was what I was looking at doing. However, after using them, we found that using blocks was pretty much vital to making our code more readable.
For developers that aren’t familiar with blocks, I’d suggest learning them. With most iOS apps having a minimum OS of 4.0, there is no reason to avoid them.