The Hopscotch Stack

In this talk, I focused primarily on the problem of surfacing good content in the Hopscotch community.

Event: http://stackuptalks.com/dev/2015/7/10/dev-stackup-ios-august-11-2015

Transcript

1. Hello! We are Thomas Abend & Nina Baculinao We are iOS and web developers at You can find us at: thomas@gethopscotch.com nina@gethopscotch.com
2. Hopscotch is a tool
3. Hopscotch is a community
4. Thomas 1. Started programming a year ago (learned Swift before Obj-C) 2. Went through Dev Bootcamp 3. Passions: music, cooking, philosophy 4. Favorite hopscotch character: Bear
5. Nina 1. Also started programming a year ago (making a game with Obj-C & Cocos2D) 2. Returned to Columbia for postbac in CS 3. Favorite Hopscotch project: Challenge: Do Stargirl's Hair! ✂
6. Our CTO Sam + We’re Hiring 1. This is our CTO and Co-Founder Sam John 2. We are hiring! Talk to us afterwards :)
7. Web • Ruby on Rails • ElasticBeanstalk • Amazon S3 • ElasticSearch • WebGL • TypeScript • Semaphore iOS • 50/50 Swift/Obj-C • MagicalRecord • AFNetworking • Kiwi • Amplitude • AppSee • Bitrise Our Stack
8. Hopscotch fun 1. Users are super creative 2. Satisfying to work with children 3. Awesome team of people
9. Technical fun 1. We are both a creative tool and a community 2. We are rendering games within games 3. We need to be COPPA compliant 4. Our app is big
10. P1: Performance limits in UIKit Problem: • Drawing our characters and text is intensive and can lead to performance issues Causes: • Users are creating increasingly complex games • Cloning allows for projects to grow in complexity exponentially • We have high quality vector images of our characters Existing code: In our HSStageObjectView: • Override drawRect with our own drawImage function • Call setNeedsDisplay to trigger redrawing
11. 500 Everythings
12. Solutions: • Create a shared ImageCache on UIView • Give the stage objects ImageViews • Trigger redraws from the StageObjectViewControler for more precision • Provide hard limits on character size and number of characters • Long term: move to Javascript and GL Takeaways: • It is kind of weird to have a game in UIKit (but cool also) • Giving the view an imageView allowed for faster scaling P1: Performance limits in UIKit
13. P2: Surfacing Good Content Problem: • As a user, I’m not always guaranteed awesome content to play when I’m exploring beyond the “Featured” channel Causes: • Spamming for likes • Using Hopscotch projects to chat • More new users (yay!) experimenting with simple projects Solution: • Extrinsic factors (number of likes, remixes, plays, recency) • Intrinsic factors (projects stored as JSON) • Bayesian classifier to identify high quality projects
15. P2: Surfacing Good Content Process: • Spend time playing Hopscotch and looking at project data to form hypotheses about useful attributes • Read about Bayesian spam filters • Build a tool to classify data for training set • Build classifier that can tell us which projects are great • Optimize and deploy code for production
16. P2: Surfacing Good Content Advantages: • Save time finding potential features • First instinct to write a bunch of boolean checks not as comprehensive • Statistical approach can evolve with trends Disadvantages: • Big time investment labeling • “Greatness” is a subjective measure • High standard deviations • Tradeoff between false positives (spam mistakenly identified as ham) and false negatives (the opposite) • Still requires manual curation
17. P3: Being Cross-Platform Problem: • Not everyone in the world has an iPad Solution: • A hopscotch web player • TypeScript and WebGL
19. P3: Being Cross-Platform Advantages: • Performance benefits of WebGL • Better testing with Jasmine • TypeScript ~= Swift • Javascript Ecosystem Disadvantages: • Time investment • Tooling around TypeScript Takeaways: • Made us want to do more Javascript
20. What’s next for Hopscotch? 1. Getting “older” 2. Getting onto more platforms (iPhone, Android) 3. Increasing the power of the language
21. Questions! We are Thomas Abend & Nina Baculinao We are iOS and web developers at You can find us at: thomas@gethopscotch.com nina@gethopscotch.com