How to run Python on iPhone and iPad (offline)

How Python runs on an iPhone

Apps can bring their own Python interpreter. When it runs on the device itself, your code never needs a server, and you don't need a connection to run it.

Python Editor works this way: Python 3 runs right in the app, also offline, without an account. print() and input() work in a console like a terminal, and errors come with their line number and a hint in plain words about what went wrong.

Your first script with input()

Interactive programs are the best way to start. This one asks for your name and a few scores and prints the average. Leave the input empty to finish.

name = input("Your name: ")
scores = []

while True:
    entry = input("Score (leave empty to finish): ")
    if entry == "":
        break
    scores.append(float(entry))

if scores:
    average = sum(scores) / len(scores)
    print(f"{name}, your average is {average:.1f}")
else:
    print("No scores entered.")

• input() always returns text, so float(entry) turns it into a number.
• The while True loop runs until break is reached.
• The f-string with :.1f prints one decimal place.

Reading files from your project

Real programs often work with data. Put a file called data.csv next to your script, with a header line name,points followed by one row per person, such as Ada,42. The csv module from the standard library reads it into dictionaries.

import csv

with open("data.csv", newline="") as f:
    rows = list(csv.DictReader(f))

for row in rows:
    print(row["name"], row["points"])

best = max(rows, key=lambda row: int(row["points"]))
print("Top score:", best["name"])

• In Python Editor, every folder is a project with a file list and tabs.
• Your program reads files like data.csv from its own folder and can import your own modules.
• You can open folders from the Files app and iCloud Drive right where they are.

Which libraries are available

The whole standard library is there: math, random, csv, json, datetime, collections, re and the rest. Beyond that, Python Editor includes numpy and matplotlib, so you can calculate with arrays and draw charts offline. Other packages like pandas, scipy or sympy download the first time you import them – that one time you need an internet connection.

Not every package from PyPI works on a phone. Libraries that need a desktop window, access to hardware or a running server are usually not an option.

numpy and matplotlib on iPad

This script computes sine and cosine for 200 points and plots both curves. In Python Editor, the chart appears right in the console.

import numpy as np
import matplotlib.pyplot as plt

x = np.linspace(0, 2 * np.pi, 200)
plt.plot(x, np.sin(x), label="sin(x)")
plt.plot(x, np.cos(x), label="cos(x)")
plt.legend()
plt.title("Sine and cosine")
plt.show()

Understanding error messages

When something goes wrong, Python prints a traceback. Read it from the bottom: the last line names the error type and what happened, the lines above it show where. The ones you'll see most as a beginner:

Tips for typing Python on a touch screen

Indentation is part of Python's syntax, which makes a good editor important on a phone. Python Editor indents automatically after a colon, closes brackets and quotes, and has a bar above the keyboard with Tab, symbols and building blocks like if, for, def and class. With a hardware keyboard on iPad, keyboard shortcuts work too.

Small projects to practice with

The fastest way to learn is to build small programs you actually want to use. Short sessions on the phone suit that well: write a few lines, run them, fix the next error. Python Editor comes with 20 examples to start from – among them guess the number, rock paper scissors, prime numbers and a quiz from JSON – and each one becomes a file of your own to change. A few more ideas:

• A tip calculator that asks for the bill and the number of people
• A vocabulary trainer that picks random words with the random module
• A countdown to your next holiday with the datetime module
• A small statistics script for your own CSV data