NSData General

Convert NSData To String

	NSString *MyString = [[NSString alloc] initWithData:MyData encoding:NSUTF8StringEncoding];

	[MyString release];

Convert String To NSData

	NSData *data = [myString dataUsingEncoding:NSUTF8StringEncoding];

Length

	if (data.length > 0)

Accessing Individual Bytes

Converting the entire array

	UInt8 *bytes = (UInt8 *)data.bytes;
	if (data.length >= 4)
		NSLog(@"Byte0: %d, Byte1: %d, Byte2: %d, Byte3: %d", bytes[0], bytes[1], bytes[2], bytes[3]);

Getting selected bytes

	UInt8 DataBytes[4];		
	[FileData getBytes:DataBytes range:NSMakeRange(0, 4)];		//Get 4 bytes from index 0
	NSLog(@"Data: %d %d %d %d", DataBytes[0], DataBytes[1], DataBytes[2], DataBytes[3]);

Create NSData From File

	NSData *data = [NSData dataWithContentsOfFile:filePath];

Create NSData From String

	NSData *TxData = [@"Hello World" dataUsingEncoding:NSUTF8StringEncoding];

Create NSData From Byte Array

	UInt8 TxDataBytes[10];
	int TxDataIndex = 0;

	TxDataBytes[TxDataIndex++] = 0x01;
	TxDataBytes[TxDataIndex++] = 0x02;
	TxDataBytes[TxDataIndex++] = 0x03;
	TxDataBytes[TxDataIndex++] = 0x04;

	NSData *TxData = [NSData dataWithBytes:&TxDataBytes length:TxDataIndex];

Copy Data To Array

	NSMutableArray *ReceivedData = (NSMutableArray *)[data bytes];

Append NSData to NSData

You need to use NSMutableData so you can append:

	NSString *response = [NSString stringWithFormat:@"Hello"];
	NSMutableData *data = [[NSMutableData alloc] initWithData:[response dataUsingEncoding:NSASCIIStringEncoding]];
	[data appendData:[NSData GetBlockOfDataFromFile:MyFilePath atOffset:MyOffset withSize:MyLength]];

	...

	[data release];

Remove Bytes From NSData

You need to use NSMutableData

//Removing from the end
	[MyData setLength:[MyData length] - 4];		//Remove 4 bytes from the end

//Removing from the beginning
	[MyData replaceBytesInRange:NSMakeRange(0, 4) withBytes:NULL length:0];		//Remove 4 bytes from the start

//Removing from the middle
	[MyData replaceBytesInRange:NSMakeRange(6, 4) withBytes:NULL length:0];		//Remove 4 bytes after the first 6 bytes

Create Large Array Of NSMutableData

	//Create array of data values
	UInt8 DataBytes[4];
	NSMutableData *FileData = [[NSMutableData alloc] init];
	UInt32 DataIndex = 0;
	for (DataIndex = 0; DataIndex < (1024 * 1024 * 2); DataIndex += 4)
	{
		DataBytes[0] = (Byte)((DataIndex & 0xff000000) >> 24);
		DataBytes[1] = (Byte)((DataIndex & 0x00ff0000) >> 16);
		DataBytes[2] = (Byte)((DataIndex & 0x0000ff00) >> 8);
		DataBytes[3] = (Byte)(DataIndex & 0x000000ff);
		
		[FileData appendBytes:DataBytes length:4];
	}

	...

	[FileData release];