NSData 与 NSString，Byte数组，UIImage 的相互转换

 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[i]);



 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[i]&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);