How to customize paging in UIScrollView? - iphone

Question

I have a question in scroll view.
Right now I wrote a sample about image gallery with scroll view. I have plenty of images added into a scroll view. Each time, it display 3 images, the question is how can measure the scrolling properly. For example: the minimum each scroll is moving 1 image. Right now, I think each time I scroll, the minimum images moving are 3. That make me can't stop at the right image I want to see.
Below is the code.
- (void)layoutScrollImages
{
UIImageView *view = nil;
NSArray *subviews = [scroll 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
[scroll setContentSize:CGSizeMake((kNumImages * kScrollObjWidth), [scroll bounds].size.height)];
}
#pragma mark - View lifecycle
- (void)viewDidLoad
{
[super viewDidLoad];
// 1. setup the scrollview for multiple images and add it to the view controller
//
// note: the following can be done in Interface Builder, but we show this in code for clarity
[scroll setBackgroundColor:[UIColor blackColor]];
[scroll setCanCancelContentTouches:NO];
scroll.indicatorStyle = UIScrollViewIndicatorStyleWhite;
scroll.clipsToBounds = YES; // default is NO, we want to restrict drawing within our scrollview
scroll.scrollEnabled = YES;
// pagingEnabled property default is NO, if set the scroller will stop or snap at each photo
// if you want free-flowing scroll, don't set this property.
scroll.pagingEnabled = YES;
// 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
[scroll addSubview:imageView];
[imageView release];
}
[self layoutScrollImages];
}

Answer 1

Use this code......
-(void)scrollViewDidScroll:(UIScrollView *)scrollView
{
if(scroll.contentOffset.y> 320)
{
int y = scrollView.contentOffset.y;
y = y/3;
[scrollView setContentOffset:CGPointMake(0, y)];
}
}
Hope, this will help you...Chill

Answer 2

Subclass the content view and overwrite this function:
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
if ([self pointInside:point withEvent:event]) {
if ([[self subviews] count] > 0) {
//force return of first child, if exists
return [[self subviews] objectAtIndex:0];
} else {
return self;
}
}
return nil; }
See detail at https://github.com/taufikobet/ScrollViewCustomPaging.