Confused about Xibs and programmatically

i a newbie for iphone development. I got some questions here.

1. I know IB is a convinience tool for UI desgin and you also can do most things programmatically. I am just wondering, when should I create an interface controll without IB and why so. I am trying to form a good habit for this. Thank you very much. A friend told me that when efficiency should be considered for the application, then i should create interface controller programmatically, any other cases?

2. I am studying Learn Objective c on Mac now. It says that "Apple suggests you avoid using autorelease on your own code". So, does it mean I cannot use "autorelease" or just i should avoid using it. For example, can i use following code in my own code for iphone development?

   @Interface Test {    
      A* a;  
   }
   
   @Implementation {  
      a = [[[开发者_运维问答A alloc]init]autorelease];  
   }
   

Thank you for your time to read this. I am looking forward to answers :D.

1. Sometimes creating custom controls will require you to build them programmatically.

2. No, it's not that you can not use autorealease, it's just that using it adds to the burden of memory management. But in some cases you probably don't have an option, such as when you have a method that returns a temporary object. Using retain/release method to manually control object lifespan is the recommended way of doing things in iPhone development. Please see Autorelease pool for more details.

1. See Matt Gallagher's blog post for a discussion of efficiency. Simply put, one method is probably no more efficient than the other. This depends on your specific application, of course. Generally speaking, do what is most comfortable in designing your user interface. Make optimizations as needed.

1) If you are doing basic views that interface building has the widgets ready to go for, then use interface builder, it will make your life easier. Plus if you are just starting out it will let you get some sample code out the door faster. I'm not a huge fan of interface builder, but if you have to maintain code, you'll come across it so good thing to get familiar with it.

2) I don't think that autorelease is a bad thing. If you are writing single threaded code there is not as much to worry about. However, the thing that can come back to bite you is that you don't actually know when things will be released. So if you have programmed poorly, and try to reference an object that you have autoreleased later in code then you may get inconsistent behavior. I autorelease, but I also am very good about retain/release in other parts of my code that is passed these objects.