Hi all, I'm an engineer with 15 years experience in the simulation industry. My background is FORTRAN and ADA, and a little bit of C. As a hobby, I've taken up learning Objective C (recently become a MAC convert). The way I learn is by example. I've been scouring the Apple documentation and source code. Been a wonderful way to learn the nuances of the language. My first question has to do with methods that are called by the OS. When I began learning objective-C (and I still have mountains to learn), one of the things that was confusing me was seeing all of these methods defined in various source files with seemingly no code making calls to these methods. I soon realized that a lot of these methods are called by the IOS OS itself (for example, touch events, init, dealloc, etc.) Is there a resource that indicates which methods are called by IOS? Obviously I can find the answer on individual methods by researching them... I was more interested if there is some kind of tabular reference that summarizes what (and when) methods are called by the OS. My second question has to do with Delegates. I understand the concept of delegates and delegation. What has been throwing me for a loop is when to use them. Can any of you experienced Objective-C programmers suggest guidelines you use for deciding when to use them? Thanks for your time.