[[NSMutableArray alloc]init] causing crash

Question

I have the following class:

#import "SharedData.h"
static int selectedCountryIndex;
static NSMutableArray *imageDataObjectsArray;
@implementation SharedData
+(void)insertIntoImageDataObjectsArray:(ImageData *)imageData:(int)index{
    if (!imageDataObjectsArray)
        **imageDataObjectsArray = [[NSMutableArray alloc]init ];**

    [imageDataObjectsArray insertObject:imageData atIndex:index];
}
+(ImageData *)getFromImageDataObjectsArray:(int)index{
    return [imageDataObjectsArray objectAtIndex:index];
}
+(void)setSelectedCountryIndex:(int)selectedCountryIndexArg{
    selectedCountryIndex = selectedCountryIndexArg;
}
+(int)getSelectedCountryIndex{
    return selectedCountryIndex;
}
@end

This class is just meant to accept data from one view, and then allow another view to fetch that data. However, whenever the insertIntoImageDataObjectsArray method is called, the line marked with asterisks causes an "EXC_BAD_ACCESS" crash. This is the call to that method:

[SharedData insertIntoImageDataObjectsArray:imageDataObject :[result doubleValue]-1];

Anyone have any idea why?

The error message is in the question: "EXC_BAD_ACCESS". That's all it's giving me. — John Roberts
– John Roberts, Commented Oct 15, 2012 at 16:28

James Webster · Accepted Answer · 2012-10-15 18:40:26Z

1

I expect it is this line that is crashing:

[imageDataObjectsArray insertObject:imageData atIndex:index];

And I expect it is crashing because you are attempting to insert at an index that is larger than the array.

0 => "value1",
1 => "value2"

[imageDataObjectsArray insertObject:@"value3" atIndex:1]; would succeed and produce

0 => "value1",
1 => "value3",
2 => "value2"

Subsequently calling [imageDataObjectsArray insertObject:@"value4" atIndex:5]; would fail as index 5 > max index (2)

Or as a commenter pointed out, a negative number is also invalid as an index

edited Oct 15, 2012 at 18:40

answered Oct 15, 2012 at 16:15

James Webster

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5 Comments

John Roberts Over a year ago

I changed [imageDataObjectsArray insertObject:imageData atIndex:index]; to [imageDataObjectsArray addObject:imageData]; and I still get the same problem.

James Webster Over a year ago

Are you using ARC? It could be that your array was prematurely deallocated.

John Roberts Over a year ago

I am using ARC. How do I make sure that it isn't deallocated prematurely? I figured the whole point of making it static was that it wouldn't be deallocated.

John Roberts Over a year ago

I just noticed that 3 objects are added to the array before it crashes, if that provides any clues.

Hot Licks Over a year ago

But an invalid index would not produce a EXC_BAD_ACCESS.

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