I started my iPhone learning less than a month ago, on XCode 3.2.2 with iPhone OS 3.2 (the last rev was before 4.0). This matched up with current iPhone (SDK 3) learning resources, including this book.
Then I upgraded to XCode 3.2.3 and its SDK for iOS 4. I’m noticing where the SDK is updated to accommodate iOS4. For example, the new way the y-axis behaves for CA shadows. Or I was looking up some API details on Core Animation transactions, and I noticed that the beginAnimations:context: method is deprecated in favor of blocks. The fact that base SDKs are specified differently is the most obvious, when opening older sample code projects.
I know multiple SDKs can be installed, although I wasn’t sure if installing an older one would give me trouble due to that shared component.
Are there any known “gotchas” if I continue working through the book and XCode 3.2.3 with base sdk 4.0? I’m on chapter 7 and okay so far.