Proper fill an image larger than screen - iphone

Question

What I wanted to achieve here is simply fit the image width to the screen on both orientations and use UIScrollView to just allow scroll vertically to see the whole image.
Both viewController and view are created pragmatically.
The image loaded is larger than screen on both width and height.
Here is the related code in my viewController:
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return YES;
}
- (void)loadView {
UIScreen *screen = [UIScreen mainScreen];
CGRect rect = [screen applicationFrame];
self.view = [[UIView alloc] initWithFrame:rect];
self.view.contentMode = UIViewContentModeScaleAspectFill;
self.view.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
UIImage *img=[[UIImage alloc] initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"image" ofType:#"png"]];
UIImageView *imgView =[[UIImageView alloc] initWithImage:img];
[img release];
imgView.contentMode = UIViewContentModeScaleAspectFill;
imgView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
[self.view addSubview:imgView];
[imgView release];
}
I tried all combinations for both contentMode above, did not give me correct result.
The most close I am getting now: I manually resize imgView in loadView, portrait mode would display correctly since app always starts with portrait mode, but in landscape mode, the width fits correctly, but image is centered vertically rather than top aligned.
If I add the imgView to a scrollView, in landscape mode it looks like contentSize is not set to full image size. but when I scroll bounce I can see the image is there in full size.
Questions:
why I need to resize it manually?
in landscape mode how and where I can 'move' the imgView, so imgView.frame.origin is (0,0) and works correctly with a scroll view?
Update
I added:
imgView.clipsToBounds = YES;
and find out in landscape mode the image bounds is smaller than screen in height.
So the question becomes how to have the image view keeps original ratio (thus shows the full image always) when rotated to landscape? Do I need to manually resize it after rotation again?

Answer 1

Instead of manually take care of orientation change and change view details. I plan to follow Apple document and make separate view controllers for each orientations.
see P42 # ViewControllerProgrammingGuide:
Creating an Alternate Landscape Interface

Answer 2

Here in the code you are not using any scrollView.
You need to add that imageView to ScrollView. and set the scrollView frame as same as the main view and contentSize to imageView or image Size.

Answer 3

If you are using scroll view in the app, then have you also resized the scroll view and the subviews as well, your code if fine just try to resize the subviews as well.
I use the following code to do so.
self.homescroll.autoresizingMask=UIViewAutoresizingFlexibleWidth |UIViewAutoresizingFlexibleHeight;// | UIViewAutoresizingFlexibleRightMargin |UIViewAutoresizingFlexibleLeftMargin;
self.homescroll.autoresizesSubviews=YES;
[self.homescroll setNeedsLayout];
[self.view addSubview:homescroll];
Just resize the subviews as well.