使用NSMutableURLRequest下载的最大允许文件大小是多少

Part of the functionality Ive written for an app is downloading zip files from a server using NSMutableURLRequest. All works until I try to download a file approx greater than 12MB. The iPhone is on wireless lan. I was wondering if there is a limit or max chunk size to implement when downloading larger files? I fails for these file sizes on both simulator and device. The application just crashes and didFailWithError connection delegate is never hit.Part of the functionality Ive written for an ap