Performance is something that needs to be fine tuned. Running an application in the simulator is not enough.

Instruments, Xcode’s tool to track and analyze your application’s process, has a cool little feature that lets you turn your iPhone’s screen into a sea of red and green that came straight out of Microsoft Paint. To turn this little feature on, open up instruments and create a Core Animation instrument for the iPhone. Click on the detail view icon in the bottom left of the window, and a bunch of debug options will pop up. Check the Color Blended Layers box. Now you have a good April fools prank, but this view is actual helpful when it comes to optimizing your iPhone animation performance.

The key to this color blended layers is simple – green is opaque (good), red is transparent (bad). If your application has a table view, and you are scratching your head wondering why the table doesn’t scroll like butter, look no further than this filter (okay, make sure you reuse cells too). If you can turn your views from transparent to opaque (turning red to green) you’ll notice your table start to scroll a lot smoother. Tuning your application to animate with ease is an acquired skill. You really have to play around and see what will run smoothly. Of course, there are pros and cons to many decisions you’ll make. In terms of animation performance, the more you eliminate transparency, the greater the performance.

label.backgroundColor = [UIColor clear]; // this is not your friend

I happy to announce the shipping of Attic [iTunes Link]. Starting today, March 1st, you can find Attic on App Store shelves everywhere for $1. In a nutshell, Attic is a super cool music controller for playing those old dusty neglected albums in your iTunes music collection. Plain and simple. To mark the launch, I’ve got a few new articles written to publish this week. I’ll also be sharing my experiences promoting the application and everything that comes with that. I’ve got other exciting things in the works I’d like to share, but I’ll keep quiet on those things in the mean time.

Mail Composition

There might be a time when you need to send out a message through email. In versions prior to iPhone OS 3.0, you had to specifically open the mail application to access send an email. Now in iPhone OS 3, if a user has set up their account, you, as a developer, can imbed a modal view to send emails.

Class mailClass = (NSClassFromString(@"MFMailComposeViewController"));
// We must always check whether the current device is configured for sending emails
if (mailClass != nil && [mailClass canSendMail])
{

	[self displayComposerSheet];

}else{

	[self launchMailAppOnDevice];

}

Camera Capabilities

There isn’t a camera in the iPod Touch, but that doesn’t mean there won’t be one in the future. If your application checked whether the device was an iPhone or iPod Touch, and Apple released a iPod Touch with a camera, your app would be inaccurate. With this code below, you don’t have to worry about new devices in the future.

Class photoClass = NSClassFromString(@"UIImagePickerController");
// Check is the device has a camera...
if(photoClass != nil && [photoClass isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera])
{

	NSLog(@"Camera Ready");

}else{

	NSLog(@"No camera");

}

“It’s spam”, “It’s annoying”, “Nobody uses email anymore”. Before getting huffy and puffy about email marketing, I assure email marketing can be used to easily manage a project (and leave you grinning like the monkey). Hopefully I’ll have convinced you to try Mail Chimp or some other service when you manage your iPhone project by the end of this article for some reason or another.

I haven’t used Mail Chimp for too long, but its a great free(mium) service. When I first signed up, I was a bit scared and confused by the site, but they have well put together videos and even free service chat as well. Having said that, Mail Chimp is a really powerful way to manage contact lists, and then send out emails, HTML-rich or plain, to a large group of people. Now I’ll go into a few cases where you might find launching your next iPhone project a whole lot easier…

Beta Testing
One step developers should take before releasing an application is to beta-test. This means seeding a build of your application to up to 100 different people. With all the permissions you have to jump through to release an adhoc build, it can be a daunting task to manage 100 UDID strings and entering the information into the developer portal page. Using Mail Chimp’s sign up form, you can create a custom form that allows your beta-testers to enter in their information along with their devices UDID. After people have signed up, you can export your new list of beta testers, and upload the data into the developer portal to add those devices. You can then use Mail Chimp to email the provisioning profile and the adhoc build to distribute the application so testers can try out the application.

Fans & Potential/Previous Customers
Okay, call me crazy, but you can use MailChimp for regular email marketing campaigns too. Many iPhone developers utilize this tactic to target their audience to push sales. Notably, 1Password and TapTapTap have used emails to send out information on current and new applications. People can sign up, and you can send out updates and news about your application. Of course, MailChimp makes it for people to unsubscribe from the email list just as easy as they signed up for the email.

Friends & Family
Whenever you publish a new application, you want to hook up your friends and family with a free copy. Again, if you have a lot of people you want to give the app to, this can be a long process. You’ve got to remember everyone you want to send a promo code to, request the codes, make sure each person gets their own unique one. With Mail Chimp, you can take a care of that easily. After you’ve entered in your friends email address and info, you can append a new field called Promo. Download the excel spreadsheet (from the list tab, go to “view list”, then go to the “view all” page) of the contact information and request the necessary number of promo codes from iTunes Connect. Copy and paste the promo codes into the correct column in the excel spreadsheet, and import the data back to Mail Chimp. Make sure you check the box to auto-update so you don’t recreate the data. Finally, you can send one email with each person receiving their individual promo code using the *|PROMO|* in the email contents.

Directory Access

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *basePath = ([paths count] > 0) ? [paths objectAtIndex:0] : nil;
NSString *filePath = [basePath stringByAppendingPathComponent:@"filename.plist"];

Using Plists

The Plist file format is the best format to use when reading and writing to the iPhone’s disk. Not only is it faster (because it is native) than XML, JSON and a plain text file to read, but the code is really simple.

NSDictionary *dictionary = [NSDictionary dictionaryWithContentsOfURL:filePath];
//or
NSArray *array = [NSArray arrayWithContentsOfURL:filePath];

Then to save you data to a file:

// plistDict is a NSDictionary
NSString *error;
NSData *plistData = [NSPropertyListSerialization dataFromPropertyList:plistDict  format:NSPropertyListXMLFormat_v1_0 errorDescription:&error];
if(plistData) {
     [plistData writeToFile:filePath atomically:YES];
} else {
     NSLog(error);
     [error release];
}

Play Nicely!

Where you save your files are important for when the iPhone backups information to a computer. You want to make sure your application backup is as small as possible so you need to place information in there specific directory.

1. NSDocumentsDirectory- This data is backed up every time a user syncs their information to their computer.
2. NSCachesDirectory – This information is not backed up by syncing, but not lost once your application quits. This space is ideally where you’d want to save state information. For example, in a text messaging application, you’d might want to save the string the user entered into the application, but had yet to sent out. You definitely don’t want to back this information up, but it will be needed when the application is opened again.
3. NSTemporaryDirectory – This data is lost after your application is terminated.

If you’re are like me, you name classes, variables and methods poorly from time to time. You’ll look back on a piece of code at a latter date and scratch your head over the way you call certain functions. These days of painstakenly renaming across an entire application are gone with Snow Leopard and Xcode 3.2. Enter Refractoring! Select the string you want to replace in a file somewhere in Xcode. In this case its the application delegate class name.

A dialogue box will pop up. Enter the string of how you want the class to appear, and hit preview. It will show you which files will be modified. After hitting Apply, presto and everything is renamed.

I recently attended the New York iPhone Tech Talks World Tour event that Apple held on December 1st. Having never attended WWDC, I was impressed by the show Apple was able to put on. The event schedule was jammed packed with presentations that ranged from debugging, to audio, to OpenGL. The presenters (for the most part Apple evangelists) kept sessions lively and entertaining. I found myself not learning large amounts of new material, but taking away little tidbits of information that will help me develop. As an attendee, you could have gone to a completely different set of presentations than many other attendees and exposed yourself to different topics. You could have also spent the day having your application reviewed by an evangelist or asked questions to Apple engineers in the “lab”. Overall, the event left me wanting to attend the presentations I missed because they were scheduled alongside the presentations I did indeed attend. I was also unable to meet with an evangelist simply because time limited and I even missed the wine & cheese at the end of the day to catch a train. As Daniel Jalkut covered in an article written for TUAW.com, this event wasn’t solely for developers in the New York City area. Many developers traveled far and wide from the easter coast to attend the event. Personally, I met attendees from Conneticut, Maryland, Pennsylvania and even Florida.