Hello all,
Refer the code below to compress the video file and save the compressed file in document directory.

- (void)compressMyVideo:(NSURL *)videoPath completionBlock:(void(^)(id data, BOOL result))block{

    NSLog(@"compressing ====%@", videoPath);
    completionBlock = block;

    NSURL *videoURL = videoPath;//[NSURL fileURLWithPath:videoPath];

    NSLog(@"video url is== %@", videoURL);

    NSString *outputPath = [self outputFilePath];

    NSURL *outputURL = [NSURL fileURLWithPath:outputPath];

    [self convertVideoToLowQuailtyWithInputURL:videoURL outputURL:outputURL handler:^(AVAssetExportSession *exportSession)
     {
         if (exportSession.status == AVAssetExportSessionStatusCompleted)
         {
             printf("completed\n");

             completionBlock(outputURL, YES);
         }
         else
         {
             printf("error\n");
             completionBlock(nil, NO);
         }
     }];
}

// Getting the path of outPut file
- (NSString *)outputFilePath{

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);


    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *path = [documentsDirectory stringByAppendingPathComponent:@"compressed.MOV"]; NSFileManager *fileManager = [NSFileManager defaultManager];

//    return path;

    if ([fileManager fileExistsAtPath: path])
    {
        [fileManager removeItemAtPath:path error:nil];
    }

    path = [documentsDirectory stringByAppendingPathComponent: [NSString stringWithFormat: @"compressed.MOV"] ];

    NSLog(@"path is== %@", path);

    return path;

}


// Actual compression is here.

- (void)convertVideoToLowQuailtyWithInputURL:(NSURL*)inputURL
                                   outputURL:(NSURL*)outputURL
                                     handler:(void (^)(AVAssetExportSession*))handler
{


//    [self startCompressingTheVideo:outputURL];
//
//
//    return;
    [[NSFileManager defaultManager] removeItemAtURL:outputURL error:nil];

//    AVAssetWriter

    AVURLAsset *asset = [AVURLAsset URLAssetWithURL:inputURL options:nil];

    AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:asset presetName:AVAssetExportPresetLowQuality];


//    exportSession.fileLengthLimit = 30*1024;

    exportSession.outputURL = outputURL;
    exportSession.outputFileType = AVFileTypeQuickTimeMovie;
    [exportSession exportAsynchronouslyWithCompletionHandler:^(void)
     {
         handler(exportSession);
         //         [exportSession release];
     }];
}