AFNetworkingでHTTP GETしてファイルに保存

# import "AFHTTPRequestOperationManager.h"

-(void)downloadUrl:(NSString*)url toPath:(NSString*)path
          success :(void (^)(AFHTTPRequestOperation *operation, id responseObject))success
          failure :(void (^)(AFHTTPRequestOperation *operation, NSError *error   ))failure
          progress:(void (^)(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead))progress
{
    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
    AFHTTPRequestOperation *op = [manager GET:url
                                  parameters:nil
                                  success:success
                                  failure:failure];
    [op setDownloadProgressBlock:progress];
    op.outputStream = [NSOutputStream outputStreamToFileAtPath:path append:NO];
}

    NSString *path = [NSTemporaryDirectory() stringByAppendingPathComponent:@"tmp.bin"];
    [self downloadUrl:url toPath:path
              success:^(AFHTTPRequestOperation *operation, id responseObject) {
                  NSLog(@"DL: success");
              }
              failure:^(AFHTTPRequestOperation *operation, NSError *error) {
                  NSLog(@"DL: failed %@", error);
              }
             progress:^(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead) {
                 NSLog(@"DL: progress %d", (int)(100 * totalBytesRead / totalBytesExpectedToRead));
             }];