MK Blog » Coding

iOS4 Issue: NSURLConnection and NSOperation

Mugunth Kumar — Mon, 21 Jun 2010 13:25:43 +0000

Everyone knows NSOperation is easily the best way to automatically gain powerful multi-threading on iOS/Mac platforms. However, recently for one of my apps, I faced a issue where, the NSURLConnection’s initWithRequest method doesn’t automatically start even if you forcefully send the “start” message.

For example the below code works perfectly on iPhone OS 3.1 and below but fails on iOS 4.

- (void)start { [self willChangeValueForKey:@"isExecuting"]; _isExecuting = YES; [self didChangeValueForKey:@"isExecuting"];

NSURLRequest * request = [NSURLRequest requestWithURL:_url]; _connection = [[NSURLConnection alloc] initWithRequest:request delegate:self]; }

Seems like Apple has made a change where in if the NSURLConnection’s initWithRequest method is called from a thread that’s not the main thread, it doesn’t start downloading the URL contents immediately. The bug fix for this issue is fortunately simple.

- (void)start { [self willChangeValueForKey:@"isExecuting"]; _isExecuting = YES; [self didChangeValueForKey:@"isExecuting"];


    NSURLRequest * request = [NSURLRequest requestWithURL:_url];

    _connection = [[NSURLConnection alloc] initWithRequest:request

                                                  delegate:self];

//iOS 4 bug fix if (![NSThread isMainThread]) { [self performSelectorOnMainThread:@selector(start) withObject:nil waitUntilDone:NO]; return; } }

Hope this post solves your problem.

–
Mugunth

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iPhone Tutorial: How to send In-App SMS

Mugunth Kumar — Tue, 15 Jun 2010 10:37:39 +0000

Officially, iPhone OS 4 is out of NDA and I can’t write a post on this. If you have been reading my blogs, you might already know how to send a in-app email Sending a in-app SMS is very similar to this, but with subtle differences.

Prior to iPhone OS 4, developers have to depend on

[[UIApplication sharedApplication] openURL: @"sms:12345678"];

The problem with this is not just that it closes your app, but there is no way to specify the body content of the SMS. Secondly, you are restricted to send the SMS to only one person. However, with the new MessageUI SMS controller, you can send SMS to multiple people at the same time. You can also pre-populate the SMS body field.
Developers of famous apps like Whatsapp Messenger, copy the SMS text content to clipboard and open the SMS app to allow users to paste the content. But with this newly allowed In-App SMS sheet, users can send SMS without quitting the app.

So, Let’s get started.

Step 1:

Import the MessageUI Framework into your project and #import the header file into the “.h” file of your controller where you want to open the In-App SMS sheet.

Step 2:

You might already have a button handler IBAction where you want to send the SMS. If not create a Button on your XIB file and write IBActions for it.

Step 3:

The real code

-(IBAction) sendInAppSMS:(id) sender
{
	MFMessageComposeViewController *controller = [[[MFMessageComposeViewController alloc] init] autorelease];
	if([MFMessageComposeViewController canSendText])
	{
		controller.body = @"Hello from Mugunth";
		controller.recipients = [NSArray arrayWithObjects:@"12345678", @"87654321", nil];
		controller.messageComposeDelegate = self;
		[self presentModalViewController:controller animated:YES];
	}
}

The most important part here is the line [MFMessageComposeViewController canSendText].
When sending a in-app email, you can choose to ignore this (atleast as of now) because most of the devices would have upgraded to iPhone OS 3 and all those devices would have the ability to send in-app email. However, the same doesn’t apply to SMS. Remember that even if a device is running iPhone OS 4, if it’s an iPod touch, it will never be abel to send SMS within app.
In this case, I have used a if condition to send the SMS. Practically speaking, you should enable/disable the button the user taps to send the sms based on this. You can add the code that does this in your viewDidLoad method.

Secondly, you have to set the messageComposeDelegate to self and not delegate. If you set the controller.delegate to self, you will not get the didFinishWithResult callback and the In-App SMS sheet will not close.

Step 4:

Implement Delegate Callbacks.
In your header file, implement the callbacks, MFMessageComposeViewControllerDelegate and UINavigationControllerDelegate. If you don’t you will get a warning at the line,

 controller.delegate = self;

You have to handle a callback method of MFMessageComposeViewControllerDelegate so as to dismiss the modal view controller.

- (void)messageComposeViewController:(MFMessageComposeViewController *)controller didFinishWithResult:(MessageComposeResult)result
{
	switch (result) {
		case MessageComposeResultCancelled:
			NSLog(@"Cancelled");
			break;
		case MessageComposeResultFailed:
			UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"MyApp" message:@"Unknown Error"
														   delegate:self cancelButtonTitle:@”OK” otherButtonTitles: nil];
			[alert show];
			[alert release];
			break;
		case MessageComposeResultSent:
 
			break;
		default:
			break;
	}
 
	[self dismissModalViewControllerAnimated:YES];
}

That’s it. Your app should now be able to send SMS using the new Message UI sheet.

Where the heck is MMS in this tutorial?

As on date, the MFMessageComposeViewController doesn’t support sending MMS. The controller.body is a NSString and setting a NSData pointer obviously crashes the app. Hopefully, one day, Apple will allow sending In-App MMS and I’ll probably blog about that too…

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iPhone Tutorial: Elegant way to send formatted In-App email

Mugunth Kumar — Sun, 07 Mar 2010 06:14:08 +0000

By now, most of you know how to send emails using the Message UI framework without quitting the app. In this tutorial, we will briefly discuss the techniques for sending a HTML formatted email with user generated content. Though sending a HTML formatted email is as easy as setting the option to HTML

[picker setMessageBody:emailBody isHTML:YES];

There are some cases that this method that this method doesn’t take care of. In short, this method works great for sending “Tell a friend about this app” email. But if your app needs much more sophistication, especially, if it needs to email data created by the user, you can follow the approach I suggest. Using this method, you can also adapt your code for International support and send the same email in multiple languages without any “hard-coding”

Though the method promises some great features, it is ridiculously simple.

Step 1:

Create a HTML File with the contents of your email and add it to your project. You should NOT create any css or link it to any external CSS files. All your styles whether embedded withing the