The objection to tracing arrives before the sentence is finished. It is cheating. You are not really drawing. You will never learn anything.
It is worth knowing that this objection is quite new, and that essentially every institution that has ever successfully taught drawing has ignored it.
Tracing has always been the method
Renaissance workshops had apprentices copy the master's drawings before they were allowed to draw from life, and copy them by any means available, including pouncing — pricking holes along the lines of a drawing and dusting charcoal through them onto the sheet below. It is tracing with extra steps and it was standard practice.
Vermeer almost certainly used a camera obscura or something like it. Ingres, one of the most feared draughtsmen of the nineteenth century, traced. Disney's animators worked on light boxes, stacking drawings and tracing through the sheet beneath — the whole medium is built on it. Rotoscoping, which is tracing over filmed footage frame by frame, produced a substantial part of twentieth-century animation.
None of these people were trying to get away with something. Tracing was the method because tracing teaches a specific thing very efficiently.
What it actually teaches
Drawing badly is usually not a hand problem. It is a seeing problem. You draw an eye too high on the head because you know where eyes go, and what you know overrides what is in front of you. Beginners draw symbols — the idea of a nose, the idea of a hand — rather than shapes.
Tracing interrupts that. When you follow a line that is already there, you cannot substitute what you assume for what is present. Your hand goes where the shape goes, and after enough of it, your eye starts noticing the shape before your hand gets a chance to invent one. You learn how long things actually are relative to each other. You learn that the shadow under a jaw is a hard edge and not a smudge.
What tracing does not teach is composition, or invention, or drawing something that is not in front of you. Nobody claims it does. It is one exercise, and it is the one that most reliably gets a beginner from "I cannot draw" to "I drew that", which is the gap where most people quit.
Why a phone is a reasonable place to do this
The case against the phone is obvious. The screen is small, most people do not have a stylus for it, and a finger is a blunt instrument.
The case for it is that the phone is the only drawing surface you actually have with you.
Frequency beats session length by a wide margin when you are learning a motor skill. Twenty minutes four times a week does more than three hours on a Sunday, and the difference is not close. The iPad is in a bag at home. The phone is in your hand in a queue, on a train, in the twenty minutes before someone shows up.
The small screen also turns out to be less of a problem than it sounds for this particular exercise, because tracing at phone size forces you to work at the level of large shapes and proportion — which is the thing beginners skip and the thing that actually makes a drawing read. It is quite hard to get lost in rendering individual eyelashes on a screen that size. That constraint is doing you a favour.
A finger is fine for this. You are following a line that already exists, not trying to land a precise taper. If you want a stylus, any cheap capacitive one works; you do not need a Pencil on the phone to get the benefit.
How tracing works in drawsta
The whole loop is built to be short, because a loop that takes five minutes to set up is a loop you do not run.
Find something. The app opens to a wall of pictures rather than a blank canvas — street art and murals, modern illustration, Swiss typography, vintage ads, gig posters, skate and surf culture, patent drawings, Bauhaus. Different every visit. Everything in it is openly licensed, public domain, or original art, credited where the source provides it.
Tap it. It lands on your canvas as a ghosted trace layer: the picture, washed back, sitting under where you are about to draw. There is a slider that takes it from a faint wash to the full photograph, so you can bring it up when you are looking for an edge and push it back down when you want to see your own line.
Follow the lines. Draw over it. Layers are there if you want to keep your line work separate from a second pass.
Turn the ghost off. What is left is yours — your line, on a blank page, with nothing underneath it.
That last step is the one that matters and it is the reason the ghost is a layer rather than a background. You get to see what you actually drew, without the crutch, the moment you are done.
Honest about the iPhone version
The iPad is a better drawing surface than the iPhone. That is true of every app and it is true of this one: bigger canvas, Apple Pencil with pressure and tilt, more room for the controls that let you work finely.
The iPhone version is for frequency rather than finish. It is where you do twenty minutes of shape practice because you had twenty minutes. Your drawings sync through your own private iCloud, so something started on the phone is on the iPad when you sit down with it.
There is no account to make, no ads, and no tracking. It is free, and it needs iOS 17 or later.
If you are still not sure about tracing
Try it once with a timer. Ten minutes, one picture, trace it, then turn the ghost off and look at what is on the page.
The useful part is not the drawing. It is that you will have a fairly precise sense of which bits you got right and which bits you fudged, and that is information you did not have ten minutes earlier. Then draw the same subject again without the ghost and see how much further you get.
That gap, between the traced one and the second one, is the whole thing. It is what the apprentices were doing with the charcoal and the pinholes.