How to detect image is real image or not in iOS?

Question

Suppose, there is a PHP file in mac os x, or any other file except JPEG, JPG, or PNG.

If I click, and change extension, as below

Now, if I choose Use .png, it will become a png file, and can be seen in iOS Gallery.

Now, if a person uploads this to server, as profile picture or any way, how can I check that whether it is real image or has something else in form of PNG or JPG.

NOTE: This is only to avoid hackers or harmful scripts.

Thanks.

Answer 1

尝试mime_content_type（），然后进行按类别的条件.. http://php.net/manual/en/function.mime-content-type.php