Dstrux, a new, free\u00a0iOS\u00a0app, wants to become the Snapchat of sensitive documents. It promises to let you share files with others and set a time for the files to "self-destruct." Unfortunately, in my tests, the only thing that self-destructed was Dstrux.\nThe app is similar to Dstrux\u2019s cloud-based file sharing solution. The idea is to share links to photos or documents with someone so they can view the files within the app or using a desktop Web browser. During the sharing process, you set a self-destruct timer, and the recipient can only view the file during a designated time period of days, hours or minutes. After the time expires, the recipient can't access the files.\nDstrux also prevents recipients from forwarding, downloading or altering shared files without the sender\u2019s permission, according to the company.\n\nIt\u2019s a promising app, and one many people could benefit from, at least occasionally. However, I had nothing but bad luck, using both my own iPhone 5s and, to act as file recipient, a friend\u2019s iPhone 5.\nFirst I tried to share a PDF file from my Dropbox folder, which Dstrux automatically connects to. Though PDF is a Dstrux supported file format, I consistently received an error message that said the format wasn\u2019t supported.\nI was able to send a Word file to my friend\u2019s iPhone 5, but I couldn't view it. When I tapped the "View File" link in the email sent to his phone, I was redirected to the App Store to download the Dstrux app. After the app downloaded, I went back to the original email and tapped the "View File" link again. It opened the Dstrux app, but there was no sign of the file I\u2019d sent. I tried again with three other files, and each time the result was the same. None of the files sent to that iPhone actually showed up in the Dstrux app.\nI also tried sharing Dropbox files from my friend\u2019s iPhone, but each attempt was met with another error message: "Upload failed."\nFor secure file sharing, you\u2019ll have far better luck with WatchDox, an enterprise-level document sharing and collaboration platform with Android and iOS apps. The downside: WatchDox costs $15 a month per user for the standard version.