Amount of scrolling in scrollViewWillBeginDragging

Question

Is there any way to find how much UITableView has been scrolled in any direction ? I am interested in amount not in direction.

Can you please provide more info. Like in which sense you require this, what is the actual requirement, what are the ways you have tried? — Mrunal, Sep 06 '13 at 09:44
I am getting data from the server and displaying that data into my tableviewcell. but i want to load only 10 records at a time. for this purpose i am using limit-offset thing. but i'm not very much clear how to do this in ios. I am setting those limit-offset in NSUrl. — Uniruddh, Sep 06 '13 at 10:18
Similar questions: 1. http://stackoverflow.com/questions/5137943/how-to-know-when-uitableview-did-scroll-to-bottom-in-iphone 2. http://stackoverflow.com/questions/9786774/ios-dynamically-load-new-cell-to-the-bottom-of-a-tableview — Mrunal, Sep 06 '13 at 10:24

D-eptdeveloper · Accepted Answer · 2013-09-06T10:38:09.543

You can easily grab the exact offset of the table view by looking at its contentOffset property. For the vertical scroll, look at:

tableView.contentOffset.y;

and with this you can take your tableview to any particular location

[theTableView scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:savedScrollPosition inSection:0] atScrollPosition:UITableViewScrollPositionTop animated:NO];                        
CGPoint point = theTableView.contentOffset;
point .y -= theTableView.rowHeight;
theTableView.contentOffset = point;

for you requirement of load more cells after 10 you can use this logic

- (void)scrollViewDidScroll:(UIScrollView *)aScrollView {
    CGPoint offset = aScrollView.contentOffset;
    CGRect bounds = aScrollView.bounds;
    CGSize size = aScrollView.contentSize;
    UIEdgeInsets inset = aScrollView.contentInset;
    float y = offset.y + bounds.size.height - inset.bottom;
    float h = size.height;
    // NSLog(@"offset: %f", offset.y);   
    // NSLog(@"content.height: %f", size.height);   
    // NSLog(@"bounds.height: %f", bounds.size.height);   
    // NSLog(@"inset.top: %f", inset.top);   
    // NSLog(@"inset.bottom: %f", inset.bottom);   
    // NSLog(@"pos: %f of %f", y, h);

    float reload_distance = 10;
    if(y > h + reload_distance) {
        NSLog(@"load more rows");
    }
}

Thanks this worked for me. Just one little help. As i load new data,size of tableView will increase. So how can i adjust the height accordingly ? So data doesn't get loaded if not required. — Uniruddh, Sep 06 '13 at 12:05
you need to set tableview frame according to it's content height that might give you the solution. — D-eptdeveloper, Sep 06 '13 at 12:17

score 1 · Answer 2 · answered Sep 06 '13 at 09:56

You need to measure the contentOffset of the UITableView when dragging begins and when it ends. Take a difference between the two, it will give you the amount of change from initial to final position.

CGPoint oldOffset;
CGPoint newOffset;

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
      oldOffset = scrollView.contentOffset;
}

- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset {
      newOffset = *targetContentOffset;
      CGPoint diff = {newOffset.x - oldOffset.x, newOffset.y - oldOffset.y};

      // Where diff.x => amount of change in x-coord of offset
      // diff.y => amount of change in y coord of offset
}

Hope that helps!

score 0 · Answer 3 · answered Sep 06 '13 at 09:48

0

you can find it using below syntax...

NSLog(@"scrolled:%f",yourtableview.contentOffset.y);//y for vertical, x for horizontal

answered Sep 06 '13 at 09:48

NiravPatel

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Amount of scrolling in scrollViewWillBeginDragging

3 Answers3