Having an electronic violin tuner simplifies the process a lot! However, some teachers believe that using a tuner deprives a student from being able to hear if a note is out of tune. My experiencd opinion is that you will hear yourself playing many in- and out-of-tune notes, and that you will benefit from playing on a well-tuned instrument from the beginning...regardless of how it was tuned. You will need to eventually learn to tune your instrument from a reference pitch (as described above), especially if you intend to play with other instrumentalists or an orchestra. You can also choose to go through ear training, which isn't as hard as it sounds!
Here is the process of tuning with an electronic tuner:
The tuner that I recommend for my students is typically something like this Korg tuner, below. It's generally less than $20 and works on more instruments than just the violin. I have included a link below where you can buy this tuner if you wish (I would earn a small commission from your purchase).
Korg CA-1 Chromatic Tuner
This tuner is "chromatic" which means it will tune any instrument to whatever note you set the tuner to. It tells you if your violin is too high or too low.
Korg CA-1 Chromatic Tuner - Buy Now!
Korg (the company who made the tuner above) made an excellent information video about using this tuner to tune a violin:
Part 3 - Tune Your Violin with an Electronic Tuner Device