对于我没有合成的属性，是否需要使用ARC关键字?

I have a property that I do not synthesize, instead I create a getter and setter myself. Therefore, the ARC keywords (strong or weak) have no meaning, I assume, so I eliminate them. This works fine on Xcode 4.3, but when my coworker opens them on XCode 4.2 the compiler complains that there is no strong/weak keyword, so I instructed him to meaninglessly enter the keyword back in again. Which is correct (with or without keywords)?I have a property that I do not synthesize, ins