UITableView方法 - 委托，观察者或通知中心

Question

I have a UITableView on a ViewController which implement the delegate methods to handle the UITableView stuff - adding to the table etc. All fine, but now I need another Object to handle scrollViewDidScroll from the table.

@imp ObjecteOne <UITableviewDelegate>
        - ViewDidLoad{
        [ObjectTwo setScrollView:_tableview];
        }
@end


@imp ObjectTwo
    - (void) setScrollView:(NSScrollView)view{
     // Would you do:
     [view addObserver??? @selector("scrollViewDidScroll") // something
     or          
    }

    - (void)scrollViewDidScroll:(UIScrollView *)scrollView{
    // do stuff
    }

@end

Answer 1

About all you can do is arrange for your ViewController to forward the scroll view delegate methods to the secondary object. One of the drawbacks of the delegate model is that there can only be one delegate at a time. (A better implementation by Apple might've been to have a tableDelegate separate the scrollView delegate)