關於 NSData 的數據類型(2進制,16進制之間)及深刻剖析

1. NSData 與 NSString

NSData－> NSString

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

 

NSString－>NSData

NSString *aString = @"1234abcd";

NSData *aData = [aString dataUsingEncoding: NSUTF8StringEncoding];

 

2.NSData 與 Byte

NSData－> Byte數組

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數組－> 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數組－>16進制數

Byte *bytes = (Byte *)[aData bytes];

NSString *hexStr=@"";

for(int i=0;i<[encryData length];i++)

{

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

if([newHexStr length]==1)

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

else

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

}

NSLog(@"bytes 的16進制數爲:%@",hexStr);

 

16進制數－>Byte數組

///// 將16進制數據轉化成Byte 數組

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

int j=0;

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

for(int i=0;i<[hexString length];i++)

{

int int_ch; /// 兩位16進制數轉化後的10進制數

unichar hex_char1 = [hexString characterAtIndex:i]; ////兩位16進制數中的第一位(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]; ///兩位16進制數中的第二位(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;  ///將轉化後的數放入Byte數組裏

j++;

}

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

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

 

3. NSData 與 UIImage

NSData－>UIImage

UIImage *aimage = [UIImage imageWithData: imageData];

//例：從本地文件沙盒中取圖片並轉換爲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