Objc memory crash with autorelase

Question

I have been hunting all over my code and can't find the source of this crash: I am trying to decode an object with an NSKeyedUnarchiver and it crashes on it every time and says:

*** __NSAutoreleaseFreedObject(): release of previously deallocated object (0x1008ad200) ignored
*** __NSAutoreleaseFreedObject(): release of previously deallocated object (0x1008ab200) ignored
*** __NSAutoreleaseFreedObject(): release of previously deallocated object (0x1008a8c00) ignored

Ha my bad the reason why initWithCoder was not getting called was it was having issues with the [super initWithCoder:]; This is still driving me crazy. I looked and the pointers and the NSData objects are what are going wrong:

    vertices = malloc(size_point3D * vertexCount);
    textureCoords = malloc(size_point2D * textureCount);
    normals = malloc(size_point3D * normalCount);
    faces = malloc(sizeof(GLuint) * faceCount);


    NSData *vertexData = [[NSData alloc] initWithData:[coder decodeObjectForKey:@"vertices"]];
    NSData *textureData = [[NSData alloc] initWithData:[coder decodeObjectForKey:@"textureCoords"]];
    NSData *normalData = [[NSData alloc] initWithData:[coder decodeObjectForKey:@"normals"]];
    NSData *faceData = [[NSData alloc] initWithData:[coder decodeObjectForKey:@"faces"]];


    memcpy(vertices, [vertexData bytes],  sizeof(point3D) * vertexCount);
    memcpy(textureCoords, [textureData bytes], sizeof(point2D) * textureCount);
    memcpy(normals, [normalData bytes], sizeof(point3D) * normalCount);
    memcpy(faces, [faceData bytes], sizeof(GLuint) * faceCount);

    [vertexData release];
    [textureData release];
    [normalData release];
    [faceData release];

I have tried retaining everything in this part (even the string) but it does not help.

Answer 1

Try turning on NSZombieEnabled, this should help you track down the problem.

Answer 2

If neither tools (Run -> Run with Performance tools) and NSZombiesEnabled helps, you can override - (id)retain and - (void)release methods of the class that caused the exception. Call super implementation and log retain/release. You can break in this methods to see the call stack. This way isn't beautiful, however, it helped me few time to figure out where was an extra release/autorelease call

Answer 3

Ok this was one of the hardest bugs I have ever had to solve partly because it is so hard to debug memory problems like this. The problem was in the design I have 2 classes JGStaticModel and JGModel. Somehow the unarchiver would pick one of those at random so that initWithCoder was sent to JGModel and not JGStaticModel so I thought it was not being called then even though the values are basicly the same it had issues and crashed. The reason why I got the autorelease problem was I patched some memory problems in JGStaticModel but not JGModel so it would crash on the memory because I had not fixed it there. It was almost impossible to trace but I have figured it out thanks for all the help!