Question

Given the following property definition:

@property (nonatomic,retain) MyObject* foo;

does the following code cause a memory leak:

self.foo = [[MyObject alloc] init];

?

It looks like the alloc call increments the retain count on the object to 1, then the retain inside the property setter increases it to 1. But since the initial count is never decremented to 0, the object will stick around even when self is released. Is that analysis correct?

If so, it looks like I have two alternatives:

self.foo = [[[MyObject alloc] init] autorelease];

which is not recommended on the iPhone for performance reasons, or:

MyObject* x = [[MyObject alloc] init];
self.foo = x
[x release];

which is a bit cumbersome. Are there other alternatives?

Answer 1

You are right, self.foo = [[MyObject alloc] init]; is leaking memory. Both alternatives are correct and can be used. Regarding the autorelease in such a statement: keep in mind that the object will released by the autorelease pool as soon as the current run loop ends, but it will most probably be retained a lot longer by self, so there is no issue with memory usage spikes here.