Say it openly, since I started iOS development I have used ARC.
Here are questions:
1. Is @autoreleasepool really matters when ARC enabled?
2. Doesn't ARC handles the memory management for us?
Yes, because we care about memorys.
ARC means the compiler inserts retains and releases in all the places you should have anyway. That's it. ARC isn't GC as we all known.
Autorelease just removes a retain count from the object it does not "free" the memory immediately like in c. When the autorelease pool ends all auto released objects with a count of 0 will have their memory freed up. @Kibitz503
Sometimes we create a lot of objects. Those objects are One-Time Usage and will want to free up memory used by those.
We should put these parts of code into @autoreleasepool instead of waiting for it to be freed naturally.
Samples from @Kibitz503 again:
//Non Arc Env
@autoreleasepool
{
MyObject *obj = [[MyObject alloc] init]; // no autorelease call here
//Since MyObject is never released its a leak even when the pool exits
}
//Non Arc Env
@autoreleasepool
{
MyObject *obj = [[[MyObject alloc] init] autorelease];
//Memory is freed once the block ends
}
// Arc Env
@autoreleasepool
{
MyObject *obj = [[MyObject alloc] init];
//No need to do anything once the obj variable is out of scope there are no strong pointers so the memory will free
}
// Arc Env
MyObject *obj //strong pointer from elsewhere in scope
@autoreleasepool
{
obj = [[MyObject alloc] init];
//Not freed still has a strong pointer
}