1. NSData 與 NSString

NSData－> NSString

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

NSString－>NSData

NSString *aString = @"iu78hg";
NSData *aData = [aString dataUsingEncoding: NSUTF8StringEncoding];

2.NSData 與 Byte

NSData－> Byte數(shù)組

NSString *testString = @"iu78hgkuwhda67";
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數(shù)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(shù)組－>16進制數(shù)

Byte *bytes = (Byte *)[aData bytes];
NSString *hexStr=@"";
for(int i=0;i<[encryData length];i++)
{
NSString *newHexStr = [NSString stringWithFormat:@"%x",bytes[i]&0xff];///16進制數(shù)
if([newHexStr length]==1)
hexStr = [NSString stringWithFormat:@"%@0%@",hexStr,newHexStr];
else 
hexStr = [NSString stringWithFormat:@"%@%@",hexStr,newHexStr];
}
NSLog(@"bytes 的16進制數(shù)為:%@",hexStr);

16進制數(shù)－>Byte數(shù)組

///// 將16進制數(shù)據(jù)轉(zhuǎn)化成Byte 數(shù)組
NSString *hexString = @"3e435fab9c34891f"; //16進制字符串
int j=0;
Byte bytes[128];  ///3ds key的Byte 數(shù)組爆惧， 128位
for(int i=0;i<[hexString length];i++)
{
int int_ch;  /// 兩位16進制數(shù)轉(zhuǎn)化后的10進制數(shù)
 
unichar hex_char1 = [hexString characterAtIndex:i]; ////兩位16進制數(shù)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(shù)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(zhuǎn)化后的數(shù)放入Byte數(shù)組里
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并轉(zhuǎn)換為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);

4.UIImage 與 Byte數(shù)組

情景：用Socket上傳圖片的byte數(shù)組

//根據(jù)圖片格式不同 轉(zhuǎn)換不同的data
NSData *imageData = UIImagePNGRepresentation(img);
NSData *imageData = UIImageJPEGRepresentation(img,0.001);
//不用轉(zhuǎn)碼
[imageData bytes];//把imageData轉(zhuǎn)成byte數(shù)組 上傳imageData
//然后條用socket方法  上傳NSData類型數(shù)據(jù)