You can also just modify the customize.xml file to do this for you.
To do this, open up notepad (or wordpad doesn't really matter). Inside of notepad have it say:
<?xml version="1.0" encoding="UTF-8"?>
<customization>
<camera>
<suppress-camera-sound>true</suppress-camera-sound>
</camera>
</customization>
Then save the file as customize_upgrade.xml it must be a .xml file. Don't name it customize_upgrade.xml and have it a .txt extension. It must be .xml extension. Then just upload the file to tpa\preset\custom on your phone (you can use far or xs++ or however you like to upload files to you phone) and then just restart your phone. The nice thing about this way is all you have to do is put your phone in silent mode (which you would do anyways with leon21ca's way to not hear the key sounds) and when you take pictures it will be silent. You also can then hear the sound if it doesn't matter at times when the phone isn't in silent mode plus you get to keep all the different shutter sounds (dono if it even matters to you but the option will still be there)