CODEWITHSUNDEEP
objective-ciosxcodeuitableviewviewcontroller
Alan
Alan

Reputation: 9481

Can I detect UITableView delegates in parent class?

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!

Upvotes: 0

Views: 184

Answers (2)

Mark Granoff
Mark Granoff

Reputation: 16938

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.

Upvotes: 2

Adil Soomro
Adil Soomro

Reputation: 37729

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 :)

Upvotes: 2

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