IPhone : Not able to get NSDictionary from NSString

I am trying to get NSDictionary from NSString.

NSString *report;
NSLog(@"report=%@",report);

//log

report = {
  54a2a78f8502f958eecfcfc0 = Gjfcff;
  54a2a78f8502f958eecfcfc1 =     {
    "_id" = 539affbb012bad66a0cd1d79;
    data = "something";
  };
  "_id" = 54c77db48502f94891cb6f90;
  date = "27-01-2015 17:29:48";
  "modified_on" = "27-01-2015 17:29:48";
  "record_version" = "0.01";
  sequence = "0.02";
  status = status;
  user = 53983594012bad299f28869f;
}

//I have tried like this: -

NSData *data = [report dataUsingEncoding:NSUTF8StringEncoding];
NSLog(@"NSDATA = %@",data);

NSError* error;
NSDictionary *myData = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];

I am getting error :-

Error Domain=NSCocoaErrorDomain Code=3840 "The operation couldn’t be
completed. (Cocoa error 3840.)" (No string key for value in object
around character 6.) UserInfo=0x156dcda0 {NSDebugDescription=No
string key for value in object around character 6.}

Whats going wrong?