Objective-C Shared variables between classes - objective-c

Question

Basically I've implemented a connection method which parses a JSON from an URL, via sendAsynchronousRequest. Everything's working nicely. But at the end of the sendAsynchronousRequest function, I need to reload a tableView (since the data arrived and I need to show it).
Currently I'm doing it by sending the tableView as parameter to the function of the class that does the connection
#implementation WhosWhereConnection
- (void)setUpConnection:(UITableView *)tableView {
...
[tableView reloadData];
...
}
And calling the function with
[connection setUpConnection:self.tableView];
It's working as I intended, but I feel this ins't the most elegant way of doing it. What would you recommend?
Wish I could accept all your answers, thank you for helping :)

Answer 1

I would recommend using blocks for this. It is convenient and very strong solution.
Something like this:
Method header (.h file)
- (void)setupConnectionWithCompletion:(void(^)())completionBlock;
Method implementation (.m file)
- (void)setupConnectionWithCompletion:(void(^)())completionBlock
{
// Do your stuff
// Call completion block (if set) when everything is done
if(completionBlock) {
completionBlock();
}
}
And call it like this
[connection setupConnectionWithCompletion:^{
[tableView reloadData];
}];

Answer 2

Better to have a delegate method / block which is called on completion, or to post a notification (if multiple instances are interested in the event). This will allow you to break the dependency you currently have by making the actions performed as a result of the completion event anonymous to the WhosWhereConnection class. The simplest change will be to replace the table view parameter with a block.
Using a delegate requires the most code. The other answers show the code for the other options.
For delegation, we want:
A protocol to define method(s) that will be called
A property to hold the delegate object reference
Usage of the delegate
Implementation of the delegate method(s)
1, 2 & 3 are on WhosWhereConnectionDelegate class. 4 is on the table view controller.
1.
#protocol WhosWhereConnectionDelegate < NSObject >
- (void)connection:(WhosWhereConnectionDelegate *)connection didCompleteWithStatus:(BOOL)status;
#end
2.
#property (weak, nonatomic) id < WhosWhereConnectionDelegate > delegate;
3.
You don't show what setUpConnection does, but the delegate call should be made once the connection is complete.
- (void)setUpConnection {
BOOL status = NO;
...
// stuff here to process things and determine the status
...
[self.delegate connection:self didCompleteWithStatus:status];
...
}
4.
The table view controller sets itself as the delegate of the connection before the connection starts.
- (void)connection:(WhosWhereConnectionDelegate *)connection didCompleteWithStatus:(BOOL)status
{
[self.tableView reloadData];
}

Answer 3

NSNotifications is what you need.
- (void)setUpConnection{
//...
[[NSNotificationCenter defaultCenter] postNotificationName:#"notificationName" object:yourData];
//...
}
In your viewController:
- (void)viewDidLoad
{
//...
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(dataDidLoad:) name:#"notificationName" object:nil];
//...
}
- (void)dataDidLoad:(NSNotification*)notification
{
//do your stuff
[tebleView reloadData];
}