// Associate the device with a user
PFInstallation *installation = [PFInstallation currentInstallation];
installation[@"user"] = [PFUser currentUser];
[installation saveInBackground];

这会将用户置于Installation表的"user"列中，该列将是指向_User表的指针.

This will put the user in a column "user" in the Installation table, the column would be a pointer to the _User table.