Collection Views Diffable Data Source + Compositional Layout Marina Gornostaeva @hybridcattt Swift Island 2019 !1 

Collection Views Part 1. Diffable Data Sources • Basics • Dynamic data Part 2. Compositional Layout • Basics • Per-section layout • Advanced layouts 

Diffable Data Source • Generic • Source of truth • performBatchUpdates - gone • Free diffing and animations 

Compositional layout • Declarative • Forget index paths, think in patterns • Composable, fast • Fractional and estimated sizes 

NSCollectionLayout… • Size • Item • Group • Section 

Known bugs in Xcode 11b3 • Orthogonal layout • crazy artefacts for added/removed sections • incorrect content size w/ group insets • incorrect item width w/ item spacing • large title not always showing at first 

Next steps • Layout-margin based alignment • Environment-specific layout • Supplementary views (badges, headers) • Your own idea! 

Next steps • Estimated sizes • Layout-margin based alignment • Environment-specific layout • Supplementary views (badges, headers) • Your own idea! • Check out the repo with implementations for these ^ and all the steps from the workshop!
 https://github.com/hybridcattt/IslandGuideSample 

Thank you