Crash: UIImage style crash with code for iOS 6? - iphone

Question

Here is my code for styling an image. In the iOS4.3 & above version the code works fine, but in iOS 6, it crashes.
-(UIImage *)grayImage:(UIImage *)image
{
CGImageRef img= image.CGImage;//imageSelected.CGImage;//self.originalPhoto.CGImage;
CFDataRef dataref=CGDataProviderCopyData(CGImageGetDataProvider(img));
int length=CFDataGetLength(dataref);
UInt8 *data=(UInt8 *)CFDataGetBytePtr(dataref);
for(int index=0;index<length;index+=4){
Byte grayScale =
(Byte)(data[index+3]*.11 +
data[index + 2] * .59 +
data[index + 1] * .3);
//set the new image's pixel to the grayscale version
data[index+1] = grayScale;// Code Crash here , By SIGABRAT (Exe_Bad_Access)
data[index+2] = grayScale;
data[index+3] = grayScale;
}
// .. Take image attributes
size_t width=CGImageGetWidth(img);
size_t height=CGImageGetHeight(img);
size_t bitsPerComponent=CGImageGetBitsPerComponent(img);
size_t bitsPerPixel=CGImageGetBitsPerPixel(img);
size_t bytesPerRow=CGImageGetBytesPerRow(img);
// .. Do the pixel manupulation
CGColorSpaceRef colorspace=CGImageGetColorSpace(img);
CGBitmapInfo bitmapInfo=CGImageGetBitmapInfo(img);
CFDataRef newData=CFDataCreate(NULL,data,length);
CGDataProviderRef provider=CGDataProviderCreateWithCFData(newData);
// .. Get the Image out of this raw data
CGImageRef newImg=CGImageCreate(width,height,bitsPerComponent,bitsPerPixel,bytesPerRow,colorspace,bitmapInfo,provider,NULL,true,kCGRenderingIntentDefault);
// .. Prepare the image from raw data
UIImage* rawImage = [[UIImage alloc] initWithCGImage:newImg] ;
// .. done with all,so release the references
CFRelease(newData);
CGImageRelease(newImg);
CGDataProviderRelease(provider);
CFRelease(dataref);
return rawImage;
}
What is wrong in this code?

Answer 1

Please use CFMutableDataRef in place of CFDataRef as below
CFDataRef m_DataRef = CGDataProviderCopyData(CGImageGetDataProvider(inImage));
//->write this:
CFMutableDataRef m_DataRef = CFDataCreateMutableCopy(0, 0, CGDataProviderCopyData(CGImageGetDataProvider(inImage)));
UInt8 * m_PixelBuf = (UInt8 *) CFDataGetBytePtr(m_DataRef);
//->write this
UInt8 *m_PixelBuf=(UInt8 *)CFDataGetMutableBytePtr(m_DataRef);