iphone UIScrollView reverse order positioning - iphone

Question

I'm building an app based upon the "Scrolling" sample code that Apple provided. All is working very well. The nature of the images that I want to display, would make it desirable, if the order of the images is reversed, and that the first visible image is the right-most, rather than the left most. Basically, the user should scroll back, from right to left, rather than from left to right.
But now: I don't understand the syntax Apple is using, and I hope someone can explain to me what is going on. Here are the relevant parts of the sample app:
- (void)viewDidLoad
{
self.view.backgroundColor = [UIColor whiteColor];
// load all the images from our bundle and add them to the scroll view
NSUInteger i;
for (i = 1; i <= kNumImages; i++)
{
NSString *imageName = [NSString stringWithFormat:#"image%d.jpg", i];
UIImage *image = [UIImage imageNamed:imageName];
UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
// setup each frame to a default height and width, it will be properly placed when we call "updateScrollList"
CGRect rect = imageView.frame;
rect.size.height = kScrollObjHeight;
rect.size.width = kScrollObjWidth;
imageView.frame = rect;
imageView.tag = i; // tag our images for later use when we place them in serial fashion
[scrollView1 addSubview:imageView];
[imageView release];
}
[self layoutScrollImages]; // now place the photos in serial layout within the scrollview
}
- (void)layoutScrollImages
{
UIImageView *view = nil;
NSArray *subviews = [scrollView1 subviews];
// reposition all image subviews in a horizontal serial fashion
CGFloat curXLoc = 0;
for (view in subviews)
{
if ([view isKindOfClass:[UIImageView class]] && view.tag > 0)
{
CGRect frame = view.frame;
frame.origin = CGPointMake(curXLoc, 0);
view.frame = frame;
curXLoc += (kScrollObjWidth);
}
}
// set the content size so it can be scrollable
[scrollView1 setContentSize:CGSizeMake((kNumImages * kScrollObjWidth), [scrollView1 bounds].size.height)];
}

Answer 1

So this is what I ended up doing:
I first inverted the order of the subviews, and then I made the scrollview jump to the last 'frame', by adding the following lines:
CGPoint lastFrame = CGPointMake(((kNumImages -1) * kScrollObjWidth), 0.0f);
[scrollview setContentOffset:lastFrame];
I hope that this somehow is useful to somebody...

Answer 2

It looks like you need to modify layoutScrollImages. Initialize curXLoc to the max number needed, and decrement it in the loop.
- (void)layoutScrollImages
{
UIImageView *view = nil;
NSArray *subviews = [scrollView1 subviews];
// reposition all image subviews in a horizontal serial fashion
CGFloat curXLoc = kNumImages * kScrollObjWidth;
for (view in subviews)
{
if ([view isKindOfClass:[UIImageView class]] && view.tag > 0)
{
CGRect frame = view.frame;
frame.origin = CGPointMake(curXLoc, 0);
view.frame = frame;
curXLoc -= (kScrollObjWidth);
}
}
// set the content size so it can be scrollable
[scrollView1 setContentSize:CGSizeMake((kNumImages * kScrollObjWidth), [scrollView1 bounds].size.height)];
}