Please use code tags to surround your code, as mentioned in Using code tags properly
It makes it far easier for other programmers to read, and use your code snippet.
I would do:
if (Input.touchCount > 0)
{
// do something on touch
camSwitch = !camSwitch;
FirstPersonCam.gameObject.SetActive(camSwitch);
ThirdPersonCam.gameObject.SetActive(!camSwitch);
}
But if you require better touch handling, something like: Simple swipe and tap mobile input