Question

I’ve been struggling with this issue for days, so I hope someone can help me out…
I have a grouped UITableView with several cells. I want to draw some custom graphics above the UITableView that would scroll with the content of the table. Specifically, I want to draw a line with dots, joining the UITableViewCells (across the sections) like this:

Of course if we have more cells than what the screen is capable of displaying, the upper layer with the custom drawing should move with the underlaying cells.
I’ve tried to subclass UITableView and override it’s -drawRect method, but it didn’t work. Even if I wouldn’t call [super drawRect:rect], the table content displayed without problem.
I’ve tried to add a new subview to the UITableView, but it changes it’s size dynamically when it gets the cells and sections from its datasource… I’m out of ideas…

Although the Web is full of custom UITableViewCell samples, I haven’t managed to find anything similiar to my concept…

Can anyone help me how to achieve the above mentioned feature?

Answer 1

First your should subclass UITableView. Then create another UIView and add it as a subView of your custom UITableVIew.

Next override the contentOffset property of the UITableView.

-(void)setContentOffset:(CGPoint)contentOffset
{

    [super setContentOffset:contentOffset];

    // Custom code here. Update custom subview here.
}

This method will be called as the UITableView is scrolled. You can then adjust the offset of your subview and update its drawing.