Calculate rect in UIView after zoom in out and rotate and pan - objective-c

Question

I need to build a crop image and let the user pinch in\out and rotate the image.
I have the parent UIView that hold the UIImageView.
parent UIView is clipsToBounds = YES
the inner UIImageView is with contentMode = UIViewContentModeScaleAspectFill;
I don't understand how to calculate the crop rect.
this the parent view before pick image :
this is after the UIImageView add to parentView with frame (0,0,parent.width ,parent.height) and with UIViewContentModeScaleAspectFill.
this is after pinch in :
this is my crop code.
-(UIImage*)createImageToPost:(UIImageView*)imageView withParentView:(UIView*)paretView
{
CGRect rectToCrop = CGRectMake(paretView.frame.origin.x - imageView.frame.origin.x , paretView.frame.origin.y - imageView.frame.origin.y, fabs(paretView.frame.size.width - imageView.image.size.width), fabs(paretView.frame.size.height - imageView.image.size.height));
UIImage * newCropImage = [self cropWithImageView:imageView withCropRect:rectToCrop];
return newCropImage;
}
-(UIImage*)cropWithImageView:(UIImageView*)imageView withCropRect:(CGRect)cropRect
{
CGRect rect = CGRectMake(0, 0, imageView.image.size.width, imageView.image.size.height);
// Begin the drawing
UIGraphicsBeginImageContext(imageView.image.size);
CGContextRef ctx = UIGraphicsGetCurrentContext();
// Clear whole thing
CGContextClearRect(ctx, rect);
// Transform the image (as the image view has been transformed)
CGContextTranslateCTM(ctx, rect.size.width*0.5, rect.size.height*0.5);
CGContextConcatCTM(ctx, imageView.transform);
CGContextTranslateCTM(ctx, -rect.size.width*0.5, -rect.size.height*0.5);
// Tanslate and scale upside-down to compensate for Quartz's inverted coordinate system
CGContextTranslateCTM(ctx, 0.0, rect.size.height);
CGContextScaleCTM(ctx, 1.0, -1.0);
// Draw view into context
CGContextDrawImage(ctx, rect, imageView.image.CGImage);
// Create the new UIImage from the context
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
// End the drawing
UIGraphicsEndImageContext();
// Begin the drawing (again)
UIGraphicsBeginImageContext(cropRect.size);
ctx = UIGraphicsGetCurrentContext();
// Clear whole thing
CGContextClearRect(ctx, CGRectMake(0, 0, cropRect.size.width, cropRect.size.height));
// Translate to compensate for the different positions of the image
CGContextTranslateCTM(ctx, -((newImage.size.width*0.5)-(cropRect.size.width*0.5)),
(newImage.size.height*0.5)-(cropRect.size.height*0.5));
// Tanslate and scale upside-down to compensate for Quartz's inverted coordinate system
CGContextTranslateCTM(ctx, 0.0, cropRect.size.height);
CGContextScaleCTM(ctx, 1.0, -1.0);
// Draw view into context
CGContextDrawImage(ctx, CGRectMake(0,0,newImage.size.width,newImage.size.height), newImage.CGImage);
// Create the new UIImage from the context
newImage = UIGraphicsGetImageFromCurrentImageContext();
// End the drawing
UIGraphicsEndImageContext();
return newImage;
}
UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:#selector(pinchGestureDetected:)];
[pinchGestureRecognizer setDelegate:self];
[imageView addGestureRecognizer:pinchGestureRecognizer];
// create and configure the rotation gesture
UIRotationGestureRecognizer *rotationGestureRecognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:#selector(rotationGestureDetected:)];
[rotationGestureRecognizer setDelegate:self];
[imageView addGestureRecognizer:rotationGestureRecognizer];
// creat and configure the pan gesture
UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(panGestureDetected:)];
[panGestureRecognizer setDelegate:self];
[imageView addGestureRecognizer:panGestureRecognizer];
- (void)pinchGestureDetected:(UIPinchGestureRecognizer *)recognizer
{
UIGestureRecognizerState state = [recognizer state];
if (state == UIGestureRecognizerStateBegan || state == UIGestureRecognizerStateChanged)
{
CGFloat scale = [recognizer scale];
[recognizer.view setTransform:CGAffineTransformScale(recognizer.view.transform, scale, scale)];
[recognizer setScale:1.0];
}
}
- (void)rotationGestureDetected:(UIRotationGestureRecognizer *)recognizer
{
UIGestureRecognizerState state = [recognizer state];
if (state == UIGestureRecognizerStateBegan || state == UIGestureRecognizerStateChanged)
{
CGFloat rotation = [recognizer rotation];
[recognizer.view setTransform:CGAffineTransformRotate(recognizer.view.transform, rotation)];
[recognizer setRotation:0];
}
}
- (void)panGestureDetected:(UIPanGestureRecognizer *)recognizer
{
UIGestureRecognizerState state = [recognizer state];
if (state == UIGestureRecognizerStateBegan || state == UIGestureRecognizerStateChanged)
{
CGPoint translation = [recognizer translationInView:recognizer.view];
[recognizer.view setTransform:CGAffineTransformTranslate(recognizer.view.transform, translation.x, translation.y)];
[recognizer setTranslation:CGPointZero inView:recognizer.view];
}
}
this is the image i get after crop: