call c++ class within objective c one - c++

Question

I wrote c++ class that return uiimage (I made sure that it doesn't return null) and I am trying to call it from objective c obe (uiview based classs) as below code, the problem is that no image be displayed any suggestion to solve that , also when put the code of c++ class at the objective c class the image appear
images imaging = new images(); // the c++ class .mm file
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
NSUserDomainMask,
YES);
NSString *fullPath = [[paths lastObject] stringByAppendingPathComponent:ImageFileName];
NSLog(fullPath);
#try {
UIView* holderView = [[UIView alloc] initWithFrame:CGRectMake(0,0,self.view.bounds.size.width,self.view.bounds.size.height)];
viewer = [[UIImageView alloc] initWithFrame:[holderView frame]];
[viewer setImage:imaging->LoadImage(fullPath)];
viewer.contentMode = UIViewContentModeScaleAspectFit;
//holderView.contentMode = UIViewContentModeScaleAspectFit ;
[holderView addSubview:viewer];
[self.view addSubview:holderView];
}
#catch (NSException * e) {
NSLog(#"this was what happened: %a ",e);
}
this is a part of the loadimage, which create image from the buffer data
try{
...............
CGDataProviderRef provider = CGDataProviderCreateWithData(NULL,MyFilter->GetOutput()->GetBufferPointer(), bufferLength, NULL);
if(colorSpaceRef == NULL)
{
NSLog(#"Error allocating color space");
CGDataProviderRelease(provider);
}
CGImageRef iref = CGImageCreate(Width,Height,bitsPerComponent,bitsPerPixel,bytesPerRow, colorSpaceRef,bitmapInfo,provider,NULL,YES,renderingIntent);
CGContextRef context = NULL;
if ((Comptype==itk::ImageIOBase::SHORT)||(Comptype==itk::ImageIOBase::USHORT))
{
context = CGBitmapContextCreate(MyFilter->GetOutput()->GetBufferPointer(),
Width,
Height,
bitsPerComponent,
bytesPerRow,
colorSpaceRef,
bitmapInfo);
}
else
{
context = CGBitmapContextCreate(myimg->GetBufferPointer(),
Width,
Height,
bitsPerComponent,
bytesPerRow,
colorSpaceRef,
bitmapInfo);
}
if(context == NULL)
{
NSLog(#"Error context not created");
}
//Create the UIImage to be displayed
UIImage * uiimage = nil;
if (context)
{
CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, Width, Height), iref);
CGImageRef imageRef = CGBitmapContextCreateImage(context);
//if([UIImage respondsToSelector:#selector(imageWithCGImage:scale:orientation:)]) {
//float scale = [[UIScreen mainScreen] scale];
//uiimage = [UIImage imageWithCGImage:imageRef scale:scale orientation:UIImageOrientationUp];
//} else {
uiimage = [UIImage imageWithCGImage:imageRef];
//}
CGImageRelease(imageRef);
CGContextRelease(context);
}
CGColorSpaceRelease(colorSpaceRef);
CGImageRelease(iref);
CGDataProviderRelease(provider);
return uiimage;
//return uiimage;
}
catch (itk::ExceptionObject & e)
{
throw(e);
}

Answer 1

The code looks okay - the Objective C, Objective C++ and C++ code should all work together fine, so I'd guess the problem may be within images::LoadImage(), even though it works separately - could we see that function?

Answer 2

Did you confirm that LoadImage returns UIImage object?
UIImage *image = imaging->LoadImage(fullPath)];
NSLog(#"className of image is \"%#\"", [image className]);
[viewer setImage:image];

Answer 3

Sometimes the Obj-C objects created by class functions in Cocoa are autoreleased. You may need to do:
uiimage = [UIImage imageWithCGImage:imageRef];
[uiimage retain];
Since this is on iOS I believe this is required, since iOS does not have garbage collection like OS X Cocoa.