iPhone Development:Enable ARC for a particular file in objective C

With ARC, iPhone app developer found a great relief from handling memory management. But, do you think what happened when you want to made changes in a source code that was made when ARC is not available and now you are integrating new libraries that uses ARC.
To solve this issue we have a compiler flag “-fobjc-arc" that we need to set in build phases of our app target.
By setting the above mentioned compiler flag for your file you are telling compiler that these file uses ARC and the one that does not include it are non ARC files.