关于 NSData 的数据类型(2进制,16进制之间)及深入剖析

1. NSData 与 NSString

NSData－> NSString

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

NSString－>NSData

NSString *aString
= @"1234abcd";

NSData *aData
= [aString dataUsingEncoding: NSUTF8StringEncoding];

2.NSData 与 Byte

NSData－> Byte数组

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);

Byte数组－> 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数组－>16进制数

Byte *bytes = (Byte *)[aData
bytes];

NSString *hexStr=@"";

for(int i=0;i<[encryData length];i++)

{

NSString *newHexStr = [NSString stringWithFormat:@"%x",bytes&0xff];///16进制数

if([newHexStr length]==1)

hexStr = [NSString stringWithFormat:@"%@0%@",hexStr,newHexStr];

else

hexStr = [NSString stringWithFormat:@"%@%@",hexStr,newHexStr];

}

NSLog(@"bytes
的16进制数为:%@",hexStr);

16进制数－>Byte数组

///// 将16进制数据转化成Byte 数组

NSString *hexString
= @"3e435fab9c34891f"; //16进制字符串

int j=0;

Byte bytes[128]; ///3ds
key的Byte 数组， 128位

for(int i=0;i<[hexString length];i++)

{

int int_ch; ///
两位16进制数转化后的10进制数

unichar hex_char1 =
[hexString characterAtIndex:i]; ////两位16进制数中的第一位(高位*16)

int int_ch1;

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

int_ch1 = (hex_char1-48)*16;   ////
0 的Ascll
- 48

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

int_ch1 = (hex_char1-55)*16; ////
A 的Ascll
- 65

else

int_ch1 = (hex_char1-87)*16; ////
a 的Ascll
- 97

i++;

unichar hex_char2 =
[hexString characterAtIndex:i]; ///两位16进制数中的第二位(低位)

int int_ch2;

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

int_ch2 = (hex_char2-48); ////
0 的Ascll
- 48

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

int_ch2 = hex_char2-55; ////
A 的Ascll
- 65

else

int_ch2 = hex_char2-87; ////
a 的Ascll
- 97

int_ch = int_ch1+int_ch2;

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

bytes[j] = int_ch;  ///将转化后的数放入Byte数组里

j++;

}

NSData *newData = [[NSData alloc] initWithBytes:bytes length:128];

NSLog(@"newData=%@",newData);

3. NSData 与 UIImage

NSData－>UIImage

UIImage *aimage = [UIImage imageWithData:
imageData];

//例：从本地文件沙盒中取图片并转换为NSData

NSString *path
= [[NSBundle mainBundle
bundlePath];

NSString *name
= [NSString stringWithFormat:@"ceshi.png"];

NSString *finalPath
=
[path stringByAppendingPathComponent:name];

NSData *imageData = [NSData dataWithContentsOfFile:
finalPath];

UIImage *aimage = [UIImage imageWithData:
imageData];

UIImage－> NSData

NSData *imageData
= UIImagePNGRepresentation(aimae); 

http://w11h22j33.iteye.com/blog/1333521