The answer is in the API documentation :
-sendPasswordResetWithEmail:completion:
Initiates a reset password for this email address.
See FIRAuthErrors for a list of error codes that are common to all API methods.
In Swift 3.x and Firebase 3.x, it will look like this:
FIRAuth.auth()?.sendPasswordReset(withEmail: " email@email ") { error in
Edit:
Firebase 4 has modified the Firebase features to be more consistent with Swift's naming conventions.
Auth.auth().sendPasswordReset(withEmail: " email@email ") { error in
source share