NSMutableArray with memory leak

Question

I am using following code to create NSMutableArray. When I run the same in “Profile” mode, it is showing a memory leakage.

SampleArray.h

@interface SampleArray: NSObject {
}
@property (assign, retain) NSMutableArray *array;
@end

SampleArray.m

#import "SampleArray.h"
@implementation SampleArray
@synthesize array;
-(void) viewDidLoad {
    self.array =[ [NSMutableArray alloc] init];
}

-(void) viewWillDisappear:(BOOL)animated {
    [self.array release];
}
@end

When I am using autorelease, then I can’t able to access the same in other function or method and return null value. Please help me to find the issue.

you can't use assign and retain at the same time.

Inder Kumar Rathore
– Inder Kumar Rathore

2012-08-22 16:01:09 +00:00
Commented Aug 22, 2012 at 16:01 — Inder Kumar Rathore
– Inder Kumar Rathore, Commented Aug 22, 2012 at 16:01

CSmith · Accepted Answer · 2012-08-22 15:56:03Z

1

releasing this array in viewWilLDisappear is not a good idea, you should release in the dealloc function. You should worry about over-releasing this item and causing a program crash since viewWilLDisappear may get called multiple times during the lifetime of this ViewController.

Anyhow, you are double retaining the item beacuse your property has a retain on it (and make it nonatomic, not assign), add an autorelease to your alloc/init:

self.array =[[[NSMutableArray alloc] init] autorelease];

and move

[array release];

to your dealloc function. Or convert to ARC and don't worry any longer...

answered Aug 22, 2012 at 15:56

CSmith

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4 Comments

Arumugam Over a year ago

I released the array in dealloc method and still showing memory leak. any guess?

CSmith Over a year ago

you can NSLog the retainCount property of your object if you're unsure. When dealloc is called, it should be = 1

Arumugam Over a year ago

I am getting retainCount 2 after initialize and not able to get the retainCount in dealloc method. It is throwing error message.

Doc Over a year ago

NEVER use the retainCount property. Ever. Ever Ever. Horrible advice. See whentouseretaincount.com

glenn sayers · Accepted Answer · 2012-08-22 15:52:09Z

0

Try setting it to (nonatomic, retain), then autoreleasing.

answered Aug 22, 2012 at 15:52

glenn sayers

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1 Comment

Arumugam Over a year ago

sorry, i am using (nonatomic, retain)

Raymond Wang · Accepted Answer · 2012-08-22 16:04:40Z

0

It is better to handle memory de-allocation in your -dealloc() and set your array to nil to be more secure in your -viewDidUnload()

so it will be:

-(void) viewDidUnload 
{
    self.array = nil;
}

-(void) dealloc
{
    [array release];

    [super dealloc];
}

and like other people said, declare your property as (nonatomic, retain) instead of (assign, retain)

answered Aug 22, 2012 at 16:04

Raymond Wang

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Comments

Inder Kumar Rathore · Accepted Answer · 2012-08-22 16:08:19Z

First of all I'm assuming that you are using

@property (nonatomic, retain) NSMutableArray *array;

use this

-(void) viewDidLoad {
    array =[[NSMutableArray alloc] init];
}

-(void) viewWillDisappear:(BOOL)animated {
    [array release];
}

I will recommend you to use dealloc instead of viewWillDisappear

-(void) dealloc {
    [array release];
    [super dealloc];
 }

Explanation of your code

   -(void) viewDidLoad {
        // here you are allocating a mutable array thus retain count becomes one
        // then you are assigning it to the property which is retain and thus retains it
        // making the retain count 2
        self.array =[ [NSMutableArray alloc] init];
    }

    -(void) viewWillDisappear:(BOOL)animated {
        // here you are releasing it so its retain count becomes 1 from 2
        // thus shows memory leak
        [self.array release];
    }

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