CODEWITHSUNDEEP
iphoneobjective-c
prostock
prostock

Reputation: 9545

app crashing when uiimage created with +imageNamed: is released in dealloc

Why does my app crash when i try to release the image I created with +imageNamed: inside dealloc. My code is as follows:

MyClass.h:

#import <UIKit/UIKit.h>
@interface MyClass{
    UIImage *_thumbImage;
}
@property (nonatomic,retain) UIImage *thumbImage;
@end

MyClass.m:

#import "MyClass.h"
@implementation MyClass
@synthesize thumbImage = _thumbImage;
-(void)viewDidLoad{
    [super viewDidLoad];
    self.thumbImage = [UIImage imagedNamed:@"myImage.png""];
}
-(void)viewDidUnload{
    self.thumbImage = nil;
}
-(void)dealloc{
    [super dealloc];
    [_thumbImage release]; //if i leave this here, the app crashes.  should i release my property?
}


@end

Upvotes: 0

Views: 471

Answers (4)

JustSid
JustSid

Reputation: 25318

You need to release your stuff first, then call [super dealloc]. [super dealloc] will release the classes memory and accessing an ivar afterwards will result in an segfault.

Upvotes: 0

cduhn
cduhn

Reputation: 17918

In your dealloc method, you need to move [super dealloc] to the bottom. You're trying to access your object's instance variable after it's been dealloced.

Upvotes: 3

Jordan
Jordan

Reputation: 21760

[UIImage imagedNamed:@"myImage.png""];

is autoreleased. It is also memory managed for you. If you need to release it immediately then alloc/init a UIImage or create UIImageView.

#import <UIKit/UIKit.h>
@interface MyClass{
}
@end


#import "MyClass.h"
@implementation MyClass
-(void)viewDidLoad{
    [super viewDidLoad];
    UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRect(0,0,100,200)];
    imageView.image = [UIImage imagedNamed:@"myImage.png""];
    [self.view addSubView:imageView];
    [imageView release];
}
-(void)viewDidUnload{
}
-(void)dealloc{
    [super dealloc];
}

Upvotes: 0

Brenton Morse
Brenton Morse

Reputation: 2567

You might want to review apples memory management guide here:

http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/MemoryMgmt/MemoryMgmt.html

Particularly the section stating:

You take ownership of an object if you create it using a method whose name begins with “alloc”, “new”, “copy”, or “mutableCopy” (for example, alloc, newObject, or mutableCopy), or if you send it a retain message.

Since you are not using one of these functions you do not have ownership of the object and therefore can not release it.

Upvotes: -1

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