NSData 與 NSString，Byte數組，UIImage 的相互轉換

 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[i]);
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[i]&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進制數為:%@",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進制數轉化后的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;  ///將轉化后的數放入Byte數組里
j++;
}
NSData *newData = [[NSData alloc] initWithBytes:bytes length:128];
NSLog(@"newData=%@",newData);

NSData 與 UIImage

NSData－>UIImage
UIImage *aimage = [UIImage imageWithData: imageData];
//例：從本地文件沙盒中取圖片并轉換為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); </pre>