App Design Lab: UI/UX Practice

Great UI/UX is a stack of small decisions. App Design Lab is a hands-on workbook where you use screens that get those decisions wrong, then see exactly why.
Each lesson tackles one decision in five steps: try a broken screen, write what felt off, see why, compare it with the fix, and write down what you learned.

23 HANDS-ON LESSONS
Try it: a sample app opens at full size with a task. The screen you are using breaks a rule on purpose.
Write it down: before you see the answer, note what you noticed.
See why: the decision, the reasoning behind it, and what falls apart if you flip it, right next to what you wrote.
Compare: switch between the broken screen and the fixed one in the same spot and spot the difference.
Write what you learned: keep one sentence you can reuse next time. Your notes collect in the Notes tab, where you can copy them or export them as a Markdown file.

A LIBRARY FOR GOING DEEPER
68 topics: toolbars, titles, search, tab bars, sheets, and text, each drawn as a mockup. Tap any part of the picture to see the rule behind it, and open a live example screen for every topic.
100 mistakes: what was done, why it seemed right at the time, and what changes once it is fixed, written as short retrospectives.
7 principles: the core judgments behind all 68 topics, shown by flipping the same screen between a broken and a correct layout.
5 labs: adjust toolbar placement, scroll edge effects, text truncation, tab bar setup, and sheet height, and get a verdict in real time.
Quiz: 396 questions that ask you to look at a screen and make the call.

MADE FOR
Developers who want a reason behind every button they place
Designers who want to get comfortable with the latest toolbars, tab bars, and sheets
Teams who need to explain the why in design reviews

Try 3 lessons, 10 mistakes, the toolbar lab, and the first quiz chapter for free. The 68 topics, 7 principles, and your notes are always free.
A weekly subscription, a monthly subscription, or a one-time lifetime purchase unlocks every lesson and resource.
Subscriptions renew automatically at the same price unless canceled at least 24 hours before the period ends. Manage or cancel anytime in your App Store account settings.
Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
There is no account, and your progress and notes stay on your device. The whole app is available in English, Japanese, and Korean.