返回副本或可变对象

Which variant is more correctly?

哪个变体更正确?

//first variant
    - (NSArray*) someArray
    {
     NSMutableArray* mutArr = [[NSMutableArray alloc] init];

     //...some operations with mutArr


     NSArray* retArray = [mutArr copy];

     [mutArr release]; //remove mutArr

     return [retArray autorelease];
    }

//second variant
    - (NSArray*) someArray
    {
     NSMutableArray* mutArr = [[NSMutableArray alloc] init];

     //...some operations with mutArr 

     return (NSArray*)[mutArr autorelease];
    }
/