当多个文件同时“写入文件”时，应用程序崩溃

Here is my code.

这是我的代码。

- (void) connectionDidFinishLoading: (NSURLConnection *) connection

{
    //Each connection has its own "downloadedData".
    BOOL writeFlag = [downloadedData writeToFile: filePath atomically: YES];
}
- (void) connectio