Can I detect UITableView delegates in parent class? - objective-c

Question

I have a ViewController that imports two TableViewControllers.
I have the delegate/datasource methods executing in these subclasses, but is there anyway that the ViewController can tell when the each TableView has executed methods such as the delegate method didSelectRowAtIndexPath or do I have to add methods in each tableviewcontroller for polling if cells had been selected?
Thanks!

Answer 1

You can define your own notifications, e.g. "MyDidSelectRowAtIndexPathNotification", and make your main view controller an observer of this notification:
#define kMyDidSelectNotification #"MyDidSelectRowAtIndexPathNotification"
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(myDidSelectAction:) name:kMyDidSelectNotification object:nil];
Then, in your implementation of tableView:didSelectRowAtIndexPath, you can simply trigger this notification for all observers:
[[NSNotificationCenter defaultCenter]
postNotificationName:kMyDidSelectNotification object:nil];
You can see here that you could pass the UITableViewCell or some other object in the notification, if you need it. Your handler for the notification (myDidSelectAction: in this case) receives an NSNotification object which would contain your object passed in the postNotification operation.
While a protocol would also work, it is more complicated to setup, in my view.
Have a look at the docs for Notification Center.

Answer 2

well you can create a #protocol like this:
#protocol MyChildViewControllerDelegate<NSObject>
#optional
- (void)tablView:(UITableView *)tv didSelectRowInChildViewControllerAtIndexPath:(NSIndexPath*)indexPath;
#end
now make a property of MyChildViewControllerDelegate in class ChildViewController and #synthesize it, like this:
#property(assign, nonatomic) id<MyChildViewControllerDelegate> delegate;
Now when making an instance of ChildViewController in parent classes assign the delegate by self like this:
ChildViewController *ch = [[ChildViewController alloc] initWithBlahBlah];
ch.delegate = self;
and implement the MyChildViewControllerDelegate methods.
now when you receive any UITableViewDelegate callback in ChildViewController tell your parent classes through delegates.
- (void)tableView:(UITableView *)tView didSelectRowAtIndexPath:(NSIndexPath *)iPath
{
[delegate tablView:tView didSelectRowInChildViewControllerAtIndexPath:iPath];
}
instead of making your own MyChildViewControllerDelegate you can use apple provided UITableViewDelegate too (as you find comfort with).
Hope it helps :)