There is no cure, so yes, you will likely have mood swings your whole life.
However, medication and therapy can be very powerful at stabilizing your mood. Some people even go into remission for years with no symptoms.

Example: Dad is bipolar 1, alcohol triggered him into horrible psychotic manias, and also deep depressions. He was hospitalized 5 times, and came close to death a few times. He is now symptom free, and he has been this way for almost 20 years wiht NO MEDICATION. He is in total remission as of now.