For many, Google Calendar is an indispensable professional tool. Unfortunately, if you have a complex arrangement of calendars you may have discovered that some calendars show up on your devices and some don’t, especially if it is a calendar that was shared to you. You can hunt around in the settings for Google Calendar and for your devices, but you won’t find the magic option to enable or disable calendars. I’m not talking about the option to hide certain calendars from view temporarily; I’m referring to choosing what shows up in that list to begin with. For some reason that baffles me, Google has this setting hidden on a page that isn’t linked to within the Google Calendar website. You need to find the link within their help documentation. But if you click on this link you can choose which calendars are accessible by CalDAV clients such as Mac Calendar and iOS Calendar:
https://www.google.com/calendar/syncselect
As a bonus tip, Google recently released a native Google Calendar app recently which you may find very useful if you don’t want all of your calendars to appear in the iOS Calendar app but you still want occasional access to them. Or if you just prefer the consistency of using the Google interface. This app isn’t affected by the above setting, but works in the same way that the Google Calendar website does.