What is a one-sentence summary of the following article?
If your phone or tablet is infected, you’ll see a pop-up message that demands payment to give you back your data or security. These pop-ups may appear out of the blue, or they may occur when doing a specific action (like pressing the Home button). Ransomware hold your data for ransom until you pay up. If you don’t pay up, data in your phone or tablet will become encrypted, making it inaccessible. Try searching for the message you see in a search engine like Google to find out if other people have had success freeing their data. Even if you pay, there’s no guarantee the ransomware will be removed. In fact, it may just reactivate. Instead, find a way to remove the ransomware from your iPhone or iPad, and be prudent in trying to prevent it in the future.

Summary:
Watch out for pop-up messages. Search for the message online. Do not pay to get your data back.