The new look of iPhone OS 4 includes a 3D dock, and a customizable wallpaper.

Apple illustrates the major updates of iPhone OS 4 into “tent poles” which are described in the next section.

1. Multi-tasking

This is perhaps the biggest update to iPhone OS 4. Make no mistake, the iPhone already supports multi-tasking on some of its native applications like Mail and iPod. However, it has closed this door to third-party applications because allowing them to run in the background affects the phone’s battery life and performance.

The big question to ask is: how does iPhone OS 4 support multi-tasking without affecting performance?

Rather than allowing applications to run freely in the background, Apple’s approach is to provide a la carte multi-tasking services. This ensures that an application will only use the multi-tasking function it needs without adulterating the performance of the entire device.

The multi-tasking services that are offered for iPhone OS 4 include:

• Background Audio - this service will allow applications like Pandora, and Ambience to play audio on the background.
• Voice Over IP - this service will allow applications like Skype, and Fring to receive VoIP calls even when the application is not running.
• Background Location - this service will allow applications like Loopt and FourSquare to constantly update user location even when the application is not running. Instead of polling GPS data, this service will use triangulation to retrieve location.
• Local Notifications - this service will allow productivity applications such as to-do lists and calendars to send notifications to the phone without having to use Apple’s Push Notification Service (PNS).
• Task Finishing - this service will allow tasks that take a while to load (like uploading a picture on Facebook) to run in the background even when the application is not active.
• Fast App Switching – this service will allow an application to save its entire state (i.e. state of a chess game) to enable users to swiftly change between applications without any delay.

With the iPhone OS 4 sporting new multi-tasking capabilities, there is a lot of creative potential for forthcoming applications.

With Multi-tasking, users can switch between apps at anytime by double-clicking the home button. Running apps can be killed by tapping and holding the app icon.

2. Enterprise

Enterprises have long had rancorous feelings about supporting the iPhone. In iPhone OS 3, the iPhone had spotty support for key enterprise features that were critical to enterprise adoption.

The release of iPhone OS 4 provides some important updates that might entice Enterprise decision-makers to take a second look at the iPhone. These new features include:

• Data Protection
• Wireless App Distribution
• Improved Mail
• Mobile Device Management
• SSL VPN Support

Other major features of iPhone OS 4 include:

3. Folders

Scrolling through multiple pages before finding that favorite application? Android users don’t have a problem with this. However, with iPhone OS 4, applications can be organized and grouped into folders. Dragging the application on top of another application automatically creates a folder, reducing clutter. This also increases the current limit of 180 applications to 2160.

With Folders, apps can be organized to reduce clutter and improve usability.

4. Even Better Mail

With iPhone OS 4, the Mail application now supports a unified inbox. It also includes support for viewing messages as threads, and opening attachments using third party applications.

5. iBooks

Apple’s e-reader application that comes pre-installed on the iPad will be available to iPhone users with the update of iPhone OS 4. Similar to Amazon’s Kindle e-reader, a massive library of books can be purchased and downloaded straight from the iBooks application.

6. Game Center

With Apple’s successful business model for game development and distribution, is not surprising why Nintendo calls them “the enemy of the future”. In a move to aggrandize its market share, Apple is providing a new social platform for its avid gamers by introducing Game Center on iPhone OS 4. With Game Center, users can play multiplayer games, view ranks, and chat with their favorite buddies similar to Xbox Live.

Game Center provides a social platform for avid iPhone / iPod touch gamers similar to Xbox Live.

7. iAd

iAd is Apple’s new mobile advertising platform to help developers with revenue generation. Current ads found in most free iPhone applications resemble that of classic web banners where users are taken to an external website when clicked.  With iAds, apps can feature highly interactive ads that combine the emotion of TV with the interactivity of the web. Think of these ads as “micro-apps”, or an app within an app.

To wrap it up…

iPhone OS 4 is a major update for the OS. The addition of multi-tasking capabilities, coupled with several improvements in the user experience puts the OS ahead of its competition. Apple claims to have the best implementation of multi-tasking among its competitors. Their name will be put to the test come June.

To learn more about the upcoming iPhone OS 4.0, visit the Apple website or watch the Keynote address . If you are an official iPhone Developer, you can download a beta version of iPhone OS 4 from the developer portal.

Apple has announced a surprise event on April 8th to reveal details on the much anticipated iPhone OS 4.0.  This event should spill the beans on multi-tasking support and other new features. Im curious to see what’s in store for the future of iPhone OS…

The most straightforward method for dealing with .plist files is +[NSArray initWithContentsOfFile:path]. However, you need to specify the correct path of the plist file via [NSBundle pathForResource:plist ofType:].

Code block

- (NSArray *)arrayFromPlist: (NSString *)plist {
     NSString *path = [[NSBundle mainBundle] pathForResource:plist ofType:@"plist"];
     NSArray *array = [[NSArray alloc] initWithContentsOfFile:path];
     return array;
 }

Loading to a Dictionary

To load the contents of a .plist file to a dictionary,  instantiate a NSDictionary or NSMutableDictionary and initialize it with [NSDictionary initWithContentsOfFile:]

Code block

- (NSDictionary *)dictionaryFromPlist: (NSString *)plist {
 NSString *path = [[NSBundle mainBundle] pathForResource:plist ofType:@"plist"];
 NSDictionary *dict = [[NSDictionary alloc] initWithContentsOfFile:path];
 return dict;
}

Writing to a .plist

The easiest way to write values to a .plist file is to use a NSDictionary and modify its contents using -[NSDictionary setObject: forKey:]. To save the contents to a .plist file, use -[NSDictionary writeToFile: atomically:].

Atomically writing to a file guarantees that the file, if it exists at all, does not become corrupted even when the system should crash while writing.

Code block

NSString *path = @"Path to Plist.plist";
 NSDictionary *dict = [[NSDictionary alloc] initWithContentsOfFile:path];
[dict setObject:@"Gierad" forKey:@"name"];
[dict writeToFile:path atomically:YES];

Lastly, if you want to read/write small configurations for your app, NSUserDefaults is recommended. It contains methods to easily handle key-value pairs including floats and other objects.

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