How to add two uiscrollviews as subview - iphone

Question

After lot of research and working for days, I really need some guidance here. I am trying to add uiscrollview on top of each other. I have two UIScrollViews: ImageScrollView and MarkScrollView. I want to add MarkScrollView as subview to ImageScrollView. ImageScrollView is added to UIViewController MapImageViewController.
In ImageScrollView it consists of images which are in tiledLayer. In MarkScrollView, it consists of imageview which has a pointer image. But for some reason it cannot be added as subview to other view. I have added my code. If anybody can help me to figure out the error it will be really appreciated.
/** ImageScrollView.m It adds uiview on top of ImageScrollView***/
UIView *imageView = [[TileView alloc] initWithImageName:imageName size:imageSize];
[(TileView *)imageView setAnnotates:NO]; // ** remove this line to remove the white tile grid **
[self addSubview:imageView];
/** MarkScrollView.m It adds uiview with uiimages on top of MarkScrollView**/
UIImage *markerimage = [UIImage imageNamed:#"map.png"];
UIImageView *imageView = [[UIImageView alloc] initWithImage: markerimage];
imageView.image = markerimage;
[imageView setFrame:CGRectMake(100,100,50,50)];
imageview = [[[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 460)] autorelease];
[imageview setBackgroundColor:[UIColor blackColor]];
[imageview addSubview: imageView];
[self addSubview:imageview];
/** MapImageViewController.m It adds ImageScrollView on top of another UIScrollView pagingScrollView **/
UIScrollView *pagingScrollView;
ImageScrollView *page = [[[ImageScrollView alloc] init] autorelease];
[pagingScrollView addSubview:page];
MarkScrollView *markerScroll = [[[MarkScrollView alloc] init] autorelease];
[page addSubview:markerScroll]; /**But it never adds the other scrollview here **/
/** MapImageViewController.h **/
#interface MapImageViewController : UIViewController <UIScrollViewDelegate, UIGestureRecognizerDelegate> {
ImageScrollingView *imageScrollView;
MarkerIconsScrollView *markerScrollView;
}

Answer 1

UIScrollView *pagingScrollView;
ImageScrollView *page = [[[ImageScrollView alloc] init] autorelease];
[pagingScrollView addSubview:page];
MarkScrollView *markerScroll = [[[MarkScrollView alloc] init] autorelease];
[page addSubview:markerScroll]; /**But it never adds the other scrollview here **/
I'm noticing some things on this code snippet:
pagingScrollView is never initialized
the views that you are adding to it (provided that it actually is initialized with a valid frame), are not initialized with a frame. Always use - (id)initWithFrame:(CGRect)aRect to initialize your UIViews
Good luck!