问题
what is the difference between strong (in LLVM compiler) and retain( in GCC compiler) ?
回答1:
strong is a new feature in iOS 5 Automatic Reference Counting (ARC) which behave the same as retain in iOS 4. Referenced Article.
Also, check out this other SO question: @property definitions with ARC: strong or retain?
回答2:
strong is a new keyword that was introduced along with arc (automatic reference counting). There are a bazillion articles about it if you search google, including this one http://cupsofcocoa.com/2011/11/27/the-jungle-part-4-automatic-reference-counting/
来源：https://stackoverflow.com/questions/10299200/what-is-the-difference-between-strong-in-llvm-and-retain-in-gcc