NSString, NSData, bytes arrays-Data Conversion

1. NSData and NSString

Nsdata-> NSString

NSString *astring = [[NSString alloc] initWithData:adataencoding:NSUTF8StringEncoding];

Nsstring->nsdata

NSString *astring = @ "1234ABCD";

NSData *adata = [astring datausingencoding:nsutf8stringencoding];

2.NSData and Byte

nsdata-> byte array

NSString *teststring = @ "1234567890";

NSData *testdata = [teststring datausingencoding:nsutf8stringencoding];

byte *testbyte = (BYTE *) [testData bytes];

for (int i=0;i<[testdata length];i++)

printf ("Testbyte =%d\n", testbyte[i]);

byte array-NSData

Byte byte[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23};

NSData *adata = [[NSData alloc] Initwithbytes:byte length:24];

byte array->16 binary number

byte *bytes = (BYTE *) [aData bytes];

NSString *hexstr=@ "";

for (int i=0;i<[encrydata length];i++)

{

NSString *newhexstr = [NSString stringwithformat:@ "%x", bytes[i]&0xff];///16 binary number

if ([Newhexstr length]==1)

HEXSTR = [NSString stringwithformat:@ "%@0%@", hexstr,newhexstr];

Else

HEXSTR = [NSString stringwithformat:@ "%@%@", hexstr,newhexstr];

}

NSLog (@ "bytes 16 binary number is:%@", hexstr);

16 Binary number->byte array

Converts 16 binary data into a byte array

NSString *hexstring = @ "3e435fab9c34891f"; 16 binary string

int j=0;

Byte bytes[128]; byte array of 3DS key, 128-bit

for (int i=0;i<[hexstring length];i++)

{

int int_ch; Two-bit 16 binary number after conversion 10 binary number

Unichar hex_char1 = [hexstring characteratindex:i]; First digit in two-bit 16 decimal (high *16)

int int_ch1;

if (hex_char1 >= ' 0 ' && hex_char1 <= ' 9 ')

Int_ch1 = (hex_char1-48) *16; 0 of Ascll-48

else if (hex_char1 >= ' A ' && hex_char1 <= ' F ')

Int_ch1 = (hex_char1-55) *16; A's Ascll-65

Else

Int_ch1 = (hex_char1-87) *16; A's Ascll-97

i++;

Unichar hex_char2 = [hexstring characteratindex:i]; Second bit (low) in two-bit 16 binary digits

int int_ch2;

if (hex_char2 >= ' 0 ' && hex_char2 <= ' 9 ')

INT_CH2 = (hex_char2-48); 0 of Ascll-48

else if (hex_char1 >= ' A ' && hex_char1 <= ' F ')

INT_CH2 = hex_char2-55; A's Ascll-65

Else

INT_CH2 = hex_char2-87; A's Ascll-97

Int_ch = INT_CH1+INT_CH2;

NSLog (@ "int_ch=%d", int_ch);

BYTES[J] = int_ch; Put the converted number in a byte array

j + +;

}

NSData *newdata = [[NSData alloc] initwithbytes:bytes length:128];

NSLog (@ "newdata=%@", NewData);

3. NSData