Question 1 Solution

NSString *fileURL = @"https://s3-ap-southeast-1.amazonaws.com/haptikdev/test/Conversation.txt";
    
    NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]
                                                          delegate:self
                                                     delegateQueue:nil];
    
    NSURLSessionDownloadTask *getFile = [session downloadTaskWithURL:[NSURL URLWithString:fileURL]
                                                   completionHandler:^(NSURL * _Nullable location, NSURLResponse * _Nullable response, NSError * _Nullable error) {
                                                       
                                                       NSError *extractErr = nil;
                                                       NSString *fetchedStr = [NSString stringWithContentsOfURL:location
                                                                                                       encoding:NSUTF8StringEncoding error:&extractErr];
                                                       
                                                       NSCharacterSet *charSet = [NSCharacterSet characterSetWithCharactersInString:@"<>"];
                                                       
                                                       NSScanner *scanner = [[NSScanner alloc] initWithString:fetchedStr];
                                                       
                                                       scanner.charactersToBeSkipped = charSet;
                                                       
                                                       BOOL isName = YES;
                                                       
                                                       NSString *name;
                                                       
                                                       NSMutableDictionary *dict = [NSMutableDictionary dictionary];
                                                       
                                                       while ([scanner scanUpToCharactersFromSet:charSet intoString:&name]) {
                                                           
                                                           if (isName) {
                                                               
                                                               NSInteger senderCount = [[dict objectForKey:name] integerValue];
                                                               
                                                               [dict setObject:[NSNumber numberWithInteger:++senderCount] forKey:name];
                                                           }
                                                           
                                                           isName = !isName;
                                                       }
                                                       
                                                       NSLog(@"dict : %@", dict);
                                                       
                                                       NSNumber *maxCount        = [NSNumber numberWithInteger:0];
                                                       NSNumber *secondMaxCount  = [NSNumber numberWithInteger:0];
                                                       
                                                       for (NSString *senderName in dict) {
                                                          
                                                           NSNumber *senderTotalMsgCount = [dict objectForKey:senderName];
                                                           
                                                           if (maxCount < senderTotalMsgCount) {
                                                               
                                                               maxCount = senderTotalMsgCount;
                                                           }
                                                           else if (secondMaxCount < senderTotalMsgCount) {
                                                               
                                                               secondMaxCount = senderTotalMsgCount;
                                                           }

                                                       }
                                                       
                                                       NSArray *maxSenders = [dict allKeysForObject:maxCount];
                                                       
                                                       NSArray *secondMaxSenders = [dict allKeysForObject:secondMaxCount];
                                                       
                                                       NSLog(@"Top message senders : %@", maxSenders);
                                                       
                                                       NSLog(@"Second top message senders : %@", secondMaxSenders);
                                                   }];
    
    [getFile resume];