I\'ve been bashing my face into this one for literally days now and even though I feel constantly that I am right on the edge of revelation, I simply cannot achieve my goal.
scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0.0,0.0,ScreenWidth,ScreenHeigth)];
[scrollView setBackgroundColor:[UIColor blackColor]];
[scrollView setDelegate:self];
[scrollView setShowsHorizontalScrollIndicator:NO];
[scrollView setShowsVerticalScrollIndicator:NO];
[scrollView setMaximumZoomScale:2.0];
image=[image scaleToSize:CGSizeMake(ScreenWidth, ScreenHeigth)];
imageView = [[UIImageView alloc] initWithImage:image];
UIImageView* imageViewBk = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"background.png"]];
[self.view addSubview:imageViewBk];
CGRect rect;
rect.origin.x=0;
rect.origin.y=0;
rect.size.width = image.size.width;
rect.size.height = image.size.height;
[imageView setFrame:rect];
[scrollView setContentSize:[imageView frame].size];
[scrollView setMinimumZoomScale:[scrollView frame].size.width / [imageView frame].size.width];
[scrollView setZoomScale:[scrollView minimumZoomScale]];
[scrollView addSubview:imageView];
[[self view] addSubview:scrollView];
then you can take screen shots to your image by this
float zoomScale = 1.0 / [scrollView zoomScale];
CGRect rect;
rect.origin.x = [scrollView contentOffset].x * zoomScale;
rect.origin.y = [scrollView contentOffset].y * zoomScale;
rect.size.width = [scrollView bounds].size.width * zoomScale;
rect.size.height = [scrollView bounds].size.height * zoomScale;
CGImageRef cr = CGImageCreateWithImageInRect([[imageView image] CGImage], rect);
UIImage *cropped = [UIImage imageWithCGImage:cr];
CGImageRelease(cr);