To enable set IFileSharingEnabled key to true in Info.plist (note it is not a string)

The file share directory

When file sharing is enabled, the entire Documents folder is used for file sharing. Files that that are not intended for user access via the file sharing feature should be stored in another part of your application’s bundle (apps are rejected if files not intended for sharing are stored there).

Good Resources

http://www.raywenderlich.com/1948/how-integrate-itunes-file-sharing-with-your-ios-app

Issues getting UIFileSharingEnabled to work

http://stackoverflow.com/questions/2603865/cfbundledocumenttypes-uifilesharingenabled-issues

	[[UIDevice currentDevice] setBatteryMonitoringEnabled:YES];

Getting The Current State

	//----- DISPLAY BATTERY STATE -----
	if ([[UIDevice currentDevice] batteryState] == UIDeviceBatteryStateUnknown)
	{
		[BatteryStateLabel setText:@""];
	}
	else
	{
		NSString *BatteryString = [NSString stringWithFormat:@"Battery: %0.0f%%", [[UIDevice currentDevice] batteryLevel] * 100];

		switch ([[UIDevice currentDevice] batteryState])
		{
			case 1:
				//Battery is in use (discharging)
				break;

			case 2:
				//Battery is charging
				BatteryString = [BatteryString stringByAppendingString:@" (charging)"];
				break;

			case 3:
				//Battery is fully charged
				BatteryString = [BatteryString stringByAppendingString:@" (charged)"];
				break;

			default:
				//Battery status is unknown
				break;
		}
		[BatteryStateLabel setText:BatteryString];
	}

Good Resources

http://iphonedevelopertips.com/device/display-battery-state-and-level-of-charge.html

System alerts, such as ”Low battery, 20% of battery remaining” will call the following methods:

applicationWillResignActive called before the alert comes up

applicationDidBecomeActive called after the alert is dismissed

A typical problem is if you use applicationDidBecomeActive to detect your app starting up from a suspended state (from multitasking).  To solve this use applicationWillEnterForeground (which isn’t called after a system alert), or if you need a ‘did’ rather than a ‘will’ method then you can use this approach:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
	...
	ThisIsAppStartup = YES;
}
- (void)applicationWillEnterForeground:(UIApplication *)application
{
	ThisIsAppStartup = YES;
}
- (void)applicationDidBecomeActive:(UIApplication *)application
{
	if (ThisIsAppStartup)		//Don't do if we're just returning from a system alert like low battery
	{
		//We are here after didFinishLaunchingWithOptions and applicationWillEnterForeground
		ThisIsAppStartup = NO;
		...
	}
}

@interface ###
{
	NSMutableData *fileData;
	NSURLConnection *connectionInProgress;
}



- (void)DownloadFileFromUrl:(NSString *)fileURL;

In Your .m file

//********************************************
//********************************************
//********** DOWNLOAD FILE FROM URL **********
//********************************************
//********************************************
- (void)DownloadFileFromUrl:(NSString *)fileURL
{

	NSLog(@"Get file from URL starting");

	NSURL *url = [NSURL URLWithString:fileURL];
	NSURLRequest *request = [NSURLRequest requestWithURL:url
											 cachePolicy:NSURLRequestReloadIgnoringCacheData
										 timeoutInterval:30];

	//Clear any existing connection if there is one
	if (connectionInProgress)
	{
		[connectionInProgress cancel];
		[connectionInProgress release];
	}

	[fileData release];
	fileData = [[NSMutableData alloc] init];

	connectionInProgress = [[NSURLConnection alloc] initWithRequest:request
														   delegate:self
												   startImmediately:YES];
}

//*************************************************
//*************************************************
//********** NEXT BLOCK OF DATA RECEIVED **********
//*************************************************
//*************************************************
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
	[fileData appendData:data];
}

//******************************************
//******************************************
//********** ALL OF DATA RECEIVED **********
//******************************************
//******************************************
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
	NSLog(@"Got file from URL");

	//CONVERT TEXT FILE TO STRING
	//NSString *SourceString = [[[NSString alloc] initWithData:fileData encoding:NSUTF8StringEncoding] autorelease];
	//NSLog(@"Text file received. Contents = %@", s);

	//DISPLAY AN IMAGE FILE
	//[MyImageView setImage:[UIImage imageWithData:fileData]];

	//RELEASE CONECTION
	if (connectionInProgress)
	{
		[connectionInProgress release];
		connectionInProgress = nil;
	}
}

//***************************************
//***************************************
//********** CONNECTION FAILED **********
//***************************************
//***************************************
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
	[connectionInProgress release];
	connectionInProgress = nil;

	[fileData release];
	fileData = nil;

	NSLog(@"Get file from URL failed");
}
//*****************************
//*****************************
//********** DEALLOC **********
//*****************************
//*****************************
- (void)dealloc
{
	[fileData release];
	[connectionInProgress release];

	[super dealloc];
}

	[MyButtonName sendActionsForControlEvents: UIControlEventTouchUpInside];

Dispatch Async And Dispatch Sync

	dispatch_async(dispatch_get_main_queue(), ^{
		//Code here to which needs to update the UI in the UI thread goes here

	});

The dispatch_async() method starts an asynchronous task.  If you want to wait until the method is finished, use dispatch_sync instead (i.e. when you want to execute a block and wait for the results).

Here’s dispatch_sync with a check to see if its necessary first:

	if ([NSThread isMainThread])
	{
		[self MyMethodName];
	}
	else
	{
		dispatch_sync(dispatch_get_main_queue(), ^{
			//Update UI in UI thread here
			[self MyMethodName];
		});
	}

Useful Method To Avoid Hang If Thread Is Already Main Thread

This handy method is based on the one here at stackoverflow

void runOnMainQueueWithoutDeadlocking(void (^block)(void))
{
	if ([NSThread isMainThread])
	{
		block();
	}
	else
	{
		dispatch_sync(dispatch_get_main_queue(), block);
	}
}

Then you use this in your code

	runOnMainQueueWithoutDeadlocking(^{
		//Do stuff
	});

Perform Selector On Main Thread

When you’re using iOS >= 4, you use dispatch_async over this as it the same as like doing waitUntilDone:NO.  If you want to wait until the method is finished use dispatch_sync.

However thi sis how it works to call a method on the main thread

	[self performSelectorOnMainThread:@selector(MyMethodName) withObject:nil waitUntilDone:NO];

Is This The Main Thread?

	if ([NSThread isMainThread])

[[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleVersion"]]

		MPMusicPlayerController *iPod = [MPMusicPlayerController iPodMusicPlayer];
		float volumeLevel = iPod.volume;
		NSLog(@"Volume: %f", volumeLevel);

You need to import the MediaPlayer framework and use:

#import <MediaPlayer/MediaPlayer.h> 

Other resources

http://stackoverflow.com/questions/7255006/get-system-volume-ios

	UInt8 MyArray[10];
	MyArray[0] = 0x00;
	MyArray[1] = 0x01;

	int LengthOfMyArray = length:sizeof(MyArray);

In #ViewController.h

@interface SomeViewController : UIViewController
{
	UIView *MyView;
{
@property (nonatomic, retain) IBOutlet UIView *MyView;

In #ViewController.m

@synthesize MyView, 

- (void)viewDidUnload
{
	self.MyView = nil;
}

Moving A UIView

	CGRect frame = self.MyView.frame;
	frame.origin.x = 0;
	self.MyView.frame = frame;

Bring A View To Front

	[self.view bringSubviewToFront:MyView];

Or use this:
	MyView.layer.zPosition = 1;

Hiding A View

	self.MyView.hidden = YES;