Dismiss alert view after waiting for another object to finish working

I have a view controller, let's call it HomeViewController, that pops up an alert view without any buttons that says "Please wait while connecting to the server". While waiting, the view controller calls a method in another class (ServerConnection) which sends data to the server.

What I need to do is cancel that alert once I receive a server response, but it won't work if I do the following:

HomeViewController *hvc = [[HomeViewController alloc] init];
[hvc waitAlertCancel];

//note:waitAlertCancel is a method tha开发者_运维知识库t calls the following line of code:
[waitAlert dismissWithClickedButtonIndex:0 animated:TRUE];

What should I do to be able to cancel that alert view from another class?

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Blocks are awesome.

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If you need to call code in one class from another class after an event occurs, blocks are the perfect solution. Before blocks were available, you'd typically handle a design like this using a delegate pattern, which is fine, but it can be heavy-handed in situations like yours where you just need to dismiss an alert. So, using blocks is a much cleaner solution, IMO.

Create a method in your ServerConnection class that uses blocks for a callback. Something along the lines of

- (void) connectWithCompletionBlock(void(^))completionBlock;

Then you would call the connectWithCompletionBlock: method like this:

[myServerConnection connectWithCompletionBlock: ^ { [waitAlert dismissWithClickedButtonIndex:0 animated:TRUE]; }];

Once the ServerConnection object receives a server response, you can have it run the completion block.

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Use NSNotification. Have the object handling the server request post a notification that it is complete. Have your home view controller listen for it and respond accordingly.