Apple has a service called Find My Friends which allows an iOS user to share his or her location with other iOS users. It's a service reminiscent of Google Latitude, which was retired earlier this year.
After Latitude was retired, Google moved the service to Google+, but it has only been available to Android users up until recently.
With the latest update to the iOS Google+ app, users can now enable location sharing with friends and family members. First thing you'll need to do is download the latest update to the Google+ iOS app.
After the update is installed, make sure you have the Google Search app installed. After installing the app and setting up Google Now, you can approve its request for permission to access your location. You can set up Google Now by tapping the cards along the bottom, going through the information screen, and tapping the "I'm in" button.
With Google Search set up and running, you can go back to the Google+ app, open the menu and select Locations from the list. Odds are if you're regularly using Google+, some of your friends are already sharing their location with you. If that's the case, you'll see their locations plotted on a map.
To setup your location sharing, tap on the Settings icon, followed by Location Settings. Here, you'll be able to enable or disable location sharing, along with selecting those with whom you wish to share either your exact location (otherwise known as pinpoint), or your city location.
You can share with individual people in your circles, or with entire circles for either category.
Going forward, any time someone you're sharing your location with launches the locations section of Google+, they'll be able to view your location based on which category was assigned.
The added benefit this service has over something like Find My Friends is that it's cross-platform. Now couples and families who are into tracking each other don't have to worry about the platform others are using (as long as it's Android or iOS) to keep tabs on someone.