Saving images in string format (for use in xml) .. does not work

Question

I convert the image from the collector to nsdata (jpeg view) and then convert it to nsstring using the following code

NSData *data=UIImageJPEGRepresentation(image,1.0); NSString *imageString=[[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding]; [[NSUserDefaults standardUserDefaults] setObject:imageString forKey:@"image_name"]; 

and on the other end, where I need to display the image, uiimage is formed as follows.

  NSString *imageString=[[NSString alloc] init]; imageString=[[NSUserDefaults standardUserDefaults] objectForKey:@"image_name"]; UIImage *image=[UIImage imageWithData:[imageString dataUsingEncoding:NSUTF8StringEncoding]]; 

the image variable used in the above code is not nil, but the image formed from the data becomes null ... when i nslogged userdefaults some line is present for the key mentioned above. can someone explain why this is so .. what is the right way to do it

Answer 1

If it passes through a web server or the like, you can encapsulate it using base64 enc64 decoding or another conventional encoder.

It removes the "bad" char, i.e. spins the string during conversion and changes them to common alphabetic characters, and then back.

if this is the cause of your problems, here is a brief question that I use (which I most likely stole and adapted, but I don’t remember from whom. Sorry! :-))

base64helper.h

  #import <Foundation/Foundation.h> @interface NSData (MBBase64) 

base64helper.m

 #import "base64helper.h" static const char encodingTable[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; @implementation NSData (MBBase64) + (id)dataWithBase64EncodedString:(NSString *)string; { if (string == nil) [NSException raise:NSInvalidArgumentException format:nil]; if ([string length] == 0) return [NSData data]; static char *decodingTable = NULL; if (decodingTable == NULL) { decodingTable = malloc(256); if (decodingTable == NULL) return nil; memset(decodingTable, CHAR_MAX, 256); NSUInteger i; for (i = 0; i < 64; i++) decodingTable[(short)encodingTable[i]] = i; } const char *characters = [string cStringUsingEncoding:NSASCIIStringEncoding]; if (characters == NULL) // Not an ASCII string! return nil; char *bytes = malloc((([string length] + 3) / 4) * 3); if (bytes == NULL) return nil; NSUInteger length = 0; NSUInteger i = 0; while (YES) { char buffer[4]; short bufferLength; for (bufferLength = 0; bufferLength < 4; i++) { if (characters[i] == '\0') break; if (isspace(characters[i]) || characters[i] == '=') continue; buffer[bufferLength] = decodingTable[(short)characters[i]]; if (buffer[bufferLength++] == CHAR_MAX) // Illegal character! { free(bytes); return nil; } } if (bufferLength == 0) break; if (bufferLength == 1) // At least two characters are needed to produce one byte! { free(bytes); return nil; } // Decode the characters in the buffer to bytes. bytes[length++] = (buffer[0] << 2) | (buffer[1] >> 4); if (bufferLength > 2) bytes[length++] = (buffer[1] << 4) | (buffer[2] >> 2); if (bufferLength > 3) bytes[length++] = (buffer[2] << 6) | buffer[3]; } realloc(bytes, length); return [NSData dataWithBytesNoCopy:bytes length:length]; } - (NSString *)base64Encoding; { if ([self length] == 0) return @""; char *characters = malloc((([self length] + 2) / 3) * 4); if (characters == NULL) return nil; NSUInteger length = 0; NSUInteger i = 0; while (i < [self length]) { char buffer[3] = {0,0,0}; short bufferLength = 0; while (bufferLength < 3 && i < [self length]) buffer[bufferLength++] = ((char *)[self bytes])[i++]; // Encode the bytes in the buffer to four characters, including padding "=" characters if necessary. characters[length++] = encodingTable[(buffer[0] & 0xFC) >> 2]; characters[length++] = encodingTable[((buffer[0] & 0x03) << 4) | ((buffer[1] & 0xF0) >> 4)]; if (bufferLength > 1) characters[length++] = encodingTable[((buffer[1] & 0x0F) << 2) | ((buffer[2] & 0xC0) >> 6)]; else characters[length++] = '='; if (bufferLength > 2) characters[length++] = encodingTable[buffer[2] & 0x3F]; else characters[length++] = '='; } return [[[NSString alloc] initWithBytesNoCopy:characters length:length encoding:NSASCIIStringEncoding freeWhenDone:YES] autorelease]; } @end