How to use NSCache right.

gistfile1.m

NSCache cache = [[NSCache alloc] init];

/*
...
*/

// WRONG
id o = [cache objectForKey:ObjectKey];
if (o == nil)
{
    o = /* create object by alloc init… */;
    [cache setObject:o forKey:ObjectKey];
    NSAssert([cache objectForKey:ObjectKey] != NULL, @"NSCache may release o here!");
    [o release];
}
return o;

// RIGHT
id o = [cache objectForKey:ObjectKey];
if (o == nil)
{
    o = /* create object by alloc init… */;
    [o autorelease];
    [cache setObject:o forKey:ObjectKey];
}
return o;