NSData 与 NSString，Byte数组，UIImage 的相互转换详解手机开发

 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:@"[email protected]%@",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);