How to solve Exe Bad access when changing device to ipad retina - iphone

Question

we are developing ipad app,i am comparing two images through this code:
-(BOOL) compareTwoImages:(UIImage *) firstImage SecondImage:(UIImage *) secondImage
{
int count=0;
int match=0;
int mismatch=0;
// UIColor* color = nil;
CGImageRef inImage = [firstImage CGImage];
CGImageRef outImage =[secondImage CGImage];
// Create off screen bitmap context to draw the image into. Format ARGB is 4 bytes for each pixel: Alpa, Red, Green, Blue
CGContextRef cgctx = [self createARGBBitmapContextFromImage:inImage];//this method creates context
CGContextRef cgctx1 = [self createARGBBitmapContextFromImage:outImage];
if (cgctx == NULL) { return NO; /* error */ }
else if (cgctx1 == NULL) { return NO; /* error */ }
size_t w = CGImageGetWidth(inImage);
size_t h = CGImageGetHeight(inImage);
CGRect rect = {{0,0},{w,h}};
// Draw the image to the bitmap context. Once we draw, the memory
// allocated for the context for rendering will then contain the
// raw image data in the specified color space.
CGContextFlush(cgctx);
CGContextFlush(cgctx1);
CGContextDrawImage(cgctx, rect, inImage);
CGContextDrawImage(cgctx1, rect, outImage);
CGContextFlush(cgctx);
CGContextFlush(cgctx1);
CGContextFlush(cgctx);
CGContextFlush(cgctx1);
// Now we can get a pointer to the image data associated with the bitmap
// context.
unsigned char* data = CGBitmapContextGetData (cgctx);
unsigned char* data1 = CGBitmapContextGetData (cgctx1);
if ((data != NULL)&&(data1 != NULL))
{
//offset locates the pixel in the data from x,y.
//4 for 4 bytes of data per pixel, w is width of one row of data.
for( int yy=0;yy<h;yy++)
{
for (int xx=0; xx<w; xx++)
{
int offset = 4*((w*round(yy))+round(xx));
int alpha = data[offset];
int alpha1 = data1[offset];**//it is giving bad access here and finally crashing**
if( alpha >1 )
{
count++;
if( alpha1 > 1 )
{
match++;
}
}
if( (alpha1 >1 )&& (alpha < 1))
{
mismatch++;
}
// NSLog(#"offset: %i colors: RGB A %i %i %i %i",offset,red,green,blue,alpha);
}
}
}
// When finished, release the context
CGContextRelease(cgctx);
CGContextRelease(cgctx1);
// Free image data memory for the context
if (data) { free(data); }
if (data1) { free(data1); }
int matchPer =(int) (( (float) match/count)*100);
int misMatchPer =(int) (( (float) mismatch/count)*100);
NSLog(#"number of match px :%d mismatch px :%d total count :%d precntage %d mismathc per %d",match,mismatch,count,matchPer,misMatchPer);
if(( matchPer>70)&&(misMatchPer <2000)) {//do anything}
its is working fine in ipad when i am comparing images through this code but creating problem when i am selecting simulator hardware >>ipad retina....
i tried to catch this bad access through intruments>>zombies but unable to catch why it is crashing...

Answer 1

Just a thought: Are you changing the Simulator to iPad Retina while the app is already running in Simulator? If this is the case, you don't have to worry about the crash. This happens because you are abruptly trying to stop the execution of the app (any running app quits when you change the simulator version) instead of stopping it properly from Xcode.