How can I prevent memory warning in IOS?

How does Wikipedia prevent people from uploading malicious images onto its website?

• My friend who is a programmer was explaining how it is possible to put your own computer at risk of viruses, etc. by viewing maliciously-crafted images. How would someone prevent this? The following is an except from our conversation from his point of view. "Basically, when you view an image on your computer, a low-level program has to run to turn the image from a stream of bits into signals for your monitor to turn on or off pixels. There have been a few cases in recent memory where that low-level decoder program has a flaw where a certain sequence of bits will cause it to do something it's not supposed to. Aside, I think, back in the iOS 2 days, someone used a flaw like this to allow people to jailbreak their phones. Your virus-checker program usually only runs on files you save to your computer; it does not usually run on images embedded in a webpage or linked-to directly. In other words, just by attempting to view the file, you could infect your computer. Even then, if the CMS tries to process the image, then the server software will run. If the image was maliciously crafted to attack the server software instead of your computer software, you would only notice a broken image; but the websites servers would be compromised."

• Answer:

  First answer and I'm not a security expert. Convert all the non-JPG and PNG images into JPG or PNG. Those which are already JPG or PNG could be decoded into a bitmap (a 2D array of pixels) using a secure decoder and then re encoded into a new JPG or PNG file.