Getting Black Image on server side after posting through Json parsing - objective-c

Question

thanks in Advance..
In my app, i have to upload an image to the server, below is my code. code is working properly, as i get the response but problem is that, on server side image is just black.
sessionid=[[[NSUserDefaults standardUserDefaults] valueForKey:#"SessionID"]objectAtIndex:0];
NSLog(#" ID = %#",sessionid);
NSData *da = [NSData data];
da = UIImagePNGRepresentation(self.Profilepic);
NSString *imgStr = [da base64Encoding];
NSLog(#" %d", imgStr.length);
NSString *serverscriptpath=[NSString stringWithFormat:#"http://c4ntechnology.com/biker/web_services/ws_insert_register3.php?"];
NSString *post =[[NSString alloc] initWithFormat:#"profile_pic=%#&sessionid=%#",imgStr,sessionid];
NSLog(#"post string is :%#",post);
NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:NO];
NSString *postLength = [NSString stringWithFormat:#"%d", [postData length]];
NSLog(#"post length is :%#",postLength);
NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
NSString *script_path=[NSString stringWithFormat:#"%#",serverscriptpath];
[request setURL:[NSURL URLWithString:script_path]];
[request setHTTPMethod:#"POST"];
[request setValue:postLength forHTTPHeaderField:#"Content-Length"];
[request setValue:#"application/x-www-form-urlencoded" forHTTPHeaderField:#"Content-Type"];
[request setHTTPBody:postData];
NSLog(#"%#",script_path);
NSData *serverReply = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
NSString* responseString = [[[NSString alloc] initWithData:serverReply encoding: NSUTF8StringEncoding] autorelease];
NSDictionary *dict = [responseString JSONValue];
NSLog(#"%#",dict);
[self ReceivedResponse:dict];
-(void)ReceivedResponse:(NSDictionary *)d
{
[AlertHandler hideAlert];
NSLog(#"%#",d);
}
please any one can help me to find out problem, that why on server image is black.?
i am using NSDatAdditions.h file for converting into base64.
when i am using
NSData *imageData = UIImageJPEGRepresentation(Profilepic, 1.0);
at server side, file is not supported occurring, so i used
NSData *da = [NSData data];
da = UIImagePNGRepresentation(self.Profilepic);

Answer 1

You should try using NSUTF8StringEncoding instead of NSASCIIStringEncoding (unless you're sure that the web-server uses ASCII encoding).
If this doesn't work, I'd try the followings:
Encode image as base 64, and afterwards decode it and check if the result is ok.
If 1 passes, check exactly what the server receives (should be the same base64 string as you've sent, otherwise there's probably an issue with different encodings)
As a side note, da = [NSData data]; is useless, since you overwrite it right after, use directly NSData *da = UIImagePNGRepresentation(self.Profilepic);