LocationsX

LocationsX is a app that share the locations  and messages via iCloud without the any registration. So you should sign in to iCloud and turn on iCloud Drive.
Each group can contain the members up to a maximum of 6 members.
The group is automatically deleted after a lapse of 36 hours since the last update of group information:

1 )You create the your group
2) You send the invitation mails to your friends.
3) Your friend taps the URL on the invitation mail of mail app and joined the group. Please copy and past the URL to Safari, if you do not use mail app of iOS
So, LocationsX will launch and ask for your nickname.
4) Tap “start sharing” and you and your friend share the locations.
5) Tap “chat list” , you can show the messages from friends. 
6) Write the message to the group and tap “send messages”.
7) Tap the portrait image in Group Info, you can select the photo for your portrait. It is displayed on the icon on the map.

You can upload your location in the background if you turn on “Enable background update”.

Notes:Please pay attention to the remaining amount of the battery. Continued use of GPS running in the background location sharing can dramatically decrease battery life in similar to foreground.