Demo code on how to capture pictures from user's camera without the need to display what is being captured.
The sound played while taking a picture is played by the iOS and there is no way to disable but you can avoid it by capturing pictures when the device is muted only.
There is no official API to detect if the device is muted or not, however, there is a walk around for that. For more info check the following repo: akramhussein/Mute