@interface Student : NSObject
@property (nonatomic, retain) NSString * studentID;
@property (nonatomic, retain) NSString * studentForeName;
@property (nonatomic, retain) NSString * studentSurname;
@end

NSData *postData = [NSJSONSerialization dataWithJSONObject:[YOUR DICTIONARY] options:0 error:&error];
[request setHTTPBody:postData];

[[NSUserDefaults standardUserDefaults] setObject:[NSKeyedArchiver archivedDataWithRootObject:YOURDICTIONARY] forKey:@"MYKEY"];
[[NSUserDefaults standardUserDefaults] synchronize];

NSDictionary *mydictionary = (NSDictionary *)[NSKeyedUnarchiver unarchiveObjectWithData:[[NSUserDefaults standardUserDefaults] objectForKey:@"MYKEY"]];