Question

When transitioning to ARC, I got the following compiler error: “It is not safe to remove an unused autorelease message”.

If I simply remove the autorelease message, obj will be immediately deallocated at the end of getAutoreleasedObj, which will cause a crash in printObj. So How do I handle the autoreleased object, and convert the following code to ARC?

- (MyClass *) getAutoreleasedObj {
    MyClass *obj = [[MyClass alloc] init];
    [obj autorelease];
    return obj;
}

- (void) printObj {
NSLog(@"%@", [self getAutoreleasedObj];
}

Answer 1

You don’t have to autorelease it, because it is returned from a function, ARC will implicitly make it __autoreleasing and release it for you.

This code:

-(id) getAutoReleasedObject
{
    __autoreleasing MyClass *obj = [MyClass new];
    return obj;
}

Compiles to this:

-(id) getAutoReleasedObject 
{
    MyClass *obj = [MyClass new]; 
    return [obj autorelease];
}