iphone – NSMutableData保存到文件

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)_response {
    response = [_response retain];
    if([response expectedContentLength] < 1) {
        data = [[NSMutableData alloc] init];
    }
    else {
        data = [[NSMutableData dataWithCapacity:[response expectedContentLength]] retain];
    }
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)_data {
    [data appendData:_data];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    NSString *filePath = [[NSBundle mainBundle] pathForresource:@"file" ofType:@"txt"];

    NSLog(@"saved: %@",filePath);
    [data writeToFile:filePath atomically:YES];
    NSLog(@"downloaded file: %@",data); //all i see in log is some encoded data here
}