使用ARC重新分配对象

Question

If I've created an NSArray in the init of an object.

Then later on I want to recreate a new NSArray to the same property should I set the old one to nil first?

ie

is it ok to just go...

self.arrayProperty = [[NSArray alloc] init];

or should I do...

self.arrayProperty = nil;
self.arrayProperty = [[NSArray alloc] init];

(I'm just using an array for the sake of this example but it's a general questions about properties).

If it makes any difference, it's a strong property.

Answer 1

The first approach is fine, you don't need to set it explicitly to nil before assigning a new object, since the setter releases the backing object of the property before retaining and assigning the new one. Just what you would do under MRC (except that here you don't autorelease the object).

Answer 2

It's just the same, as with ARC an object dies when there are no more references to it. The only difference is that in the second code you're doing a useless extra operation.