iPad large NSArray - initWithObjects vs. ArrayWithObjects

Question

can anyone clear this up for me ?
I am building an iPad App that has a TableViewController that is supposed to show something between 1000 and 2000 strings. I have those NSStrings in a Singleton.
In the init Method of the Singleton I initialize an Array that holds all the data ( does not have to be the final way to do it - was just a quick copy and paste for testing )
I did an self.someArray = [[NSArray alloc]initWithObjects: followed by the large number of strings, followed by nil.
that worked fine in the simulator - but crashed with bad access on the iPad right on Application startup
If I use the convenience method [NSArray arrayWithObjects:instead - it works fine.
I looked into Instruments and the overall memory footprint of the App is just about 2,5 MB.
Now I don't know why it works the one way but not the other.
EDIT:

#import "StaticValueContainer.h"`

static StaticValueContainer* instance = nil;
@implementation StaticValueContainer
@synthesize customerRatingKeys;

+(StaticValueContainer*)sharedInstance
{
    if (instance == nil){
        instance = [[StaticValueContainer alloc]init];
    }
    return instance;
}

-(id)init
{
    if  ( ( self = [super init] ))
    {
        [self initCustomerRatingKeys];

    }
    return self;
}
-(void)init customerRatingKeys
{
 self.customerRatingKeys = [[NSArray alloc]initWithObjects:
 @"string1",
....
 @"string1245"

,nil
}

as I said: it crashes on the device with self.customerRatingKeys = [[NSArray alloc]initWithObjects: but works with *self.customerRatingKeys = [[NSArray arrayWithObjects...`

lxt · Accepted Answer · 2011-03-01 13:30:56Z

7

Well, there isn't much difference between them: arrayWithObjects returns an auto-released array that you don't need to release yourself (unless you subsequently retain it), and initWithObjects returns an array you must then release to avoid a memory leak. Performance wise there is no difference between them.

I would suggest if you're getting a bad access error using initWithObjects but not with arrayWithObjects there might be some sort of memory management error in your code. If you post the code itself you'll probably get a more exact response.

answered Mar 1, 2011 at 13:30

lxt

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5 Comments

HeikoG Over a year ago

yes - this is the difference I know about... But i cant figure out how this is related to this crash. Maybe there is something wrong from a memory perspective, I added some code, maybe that helps to clear things up

lxt Over a year ago

self.customerRatingKeys = [[NSArray alloc]initWithObjects: - you shouldn't be doing this, assuming your property is declared as retain (which is typically would be). How are you declaring your property?

HeikoG Over a year ago

Yes I declare it with retain. What problem am I missing ?

lxt Over a year ago

Because if you've declared your property as retain you're retaining your array twice, which is going to cause a memory leak. You should add an 'autorelease' as follows: self.customerRatingsKeys = [[[NSArray alloc] initWithObjects:...]autorelease]

HeikoG Over a year ago

Right. Understand that. That is why I used the arrayWithObjects method in the first place. I thought that would create an autoreleased object ?

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