Scrap Paper is a series of tutorials about how to build a iOS notes / writing app in Swift and SwiftUI.
No! The App Store is full of excellent writing and notes apps! (I am particularly fond of Bear, Ulysses, and iA Writer. Check them out!) However, I’ve been tinkering with home-grown notes apps for over a year as a way to learn new things and have fun programming. Then I saw Nick Lockwood’s cool retro rampage tutorial series, and it inspired me to turn what I’ve learned in my little Notes apps into a tutorial series of my own.
Scrap Paper embraces the “plain text” ethos. The mental model it supports is “my notes are just text files in a directory,” and in the early stages of the tutorial that will be the implementation. (Later steps will explore the tradeoffs of storing the notes in a database.) Like many iOS writing apps, Scrap Paper will support simple formatting, links, and embedded images through Markdown-inspired syntax. Notes locked to a single device aren’t that useful, so Scrap Paper will use iCloud to synchronize notes across your devices.
Things this tutorial will cover:
- The basics of working with Core Text
- Editing text efficiently in a Piece Table
- Parsing Expression Grammars
- Incremental Packrat Parsing
- Moving beyond plain text: Databases, SQLite, and iCloud synchronization
- I assume you know the basics of Swift — this isn’t a language tutorial.
- I assume you know the concepts behind SwiftUI. However, I don’t think anyone’s an expert at SwiftUI yet, so we’ll be discovering things about SwiftUI together.
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In this part, we start with the absolute basics for a writing app -- loading, editing, and saving plain text.
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We're going to write our first custom collection type in Swift! While you may think of a text file as an array of characters, an array is an inefficient data structure for editing text. In an array, it's too expensive to make changes in the middle of a file. We'll explore other structures more suitable for text editing, and implement one of them -- a piece table. We'll make our piece table implementation conform to
CollectionandRangeReplaceableCollectionso it feels like a first-class citizen in Swift.