iOS (UIKit)

ios-uikit renders real UINavigationController pushes, a real UITabBarController, and system text handling — driven from Rust through objc2. The scaffold is a checked-in Xcode project whose build phase calls back into day, so Xcode, day launch and CI all build the same way.

Home

Controls

Date & time

Stack

Getting started

xcode-select --install          # plus Xcode itself, with an iOS Simulator runtime
cargo install day-cli
day new app my-app --toolkit ios-uikit
cd my-app
day launch -p ios-uikit          # boots a Simulator and installs

day doctor --toolkit uikit verifies Xcode, the Simulator runtimes and the Rust iOS targets. Opening platform/ios/Runner.xcodeproj in Xcode works too — ⌘R builds the same Rust library through the project’s build phase.

Packaging produces a device .ipa:

day pack -p ios-uikit

With signing.ios configured you get a signed App Store export; without it you get an unsigned device build (<name>-unsigned.ipa) for sideloading or your own signing. See packaging.

Caveats and special considerations

Development is Simulator-first. Device debugging works but gets far less use than the Simulator path.
Declare permissions before you use them. A gated API without its NS*UsageDescription key terminates the app on first use. Day generates those keys from your [permissions] table — day lint fails the build when one is missing, which is the difference between a CI failure and a crash on a tester’s phone.
No combo box. day-piece-combobox has no UIKit arm, because iOS has no native combo-box control; it renders as a placeholder. Use picker().menu().
No menu bar. iOS has no persistent menu bar, so set_app_menu is a no-op; context menus work (UIContextMenuInteraction).
Window screenshots aren’t implemented in-process — the walkthrough uses simctl io booted screenshot instead.
Dynamic Type is live: labels set adjustsFontForContentSizeCategory, so text rescales with the user’s system setting and your layout has to tolerate it.

What each piece becomes

Day piece	UIKit class
`column` / `row` / `stack` / `section`	`UIView`
`label`	`UILabel`
`button`	`UIButton` (system type; bordered/prominent use `UIButtonConfiguration`)
`toggle`	`UISwitch`
`slider`	`UISlider`
`text_field`	`UITextField`
`text_area`	`UITextView`
`picker().segmented()`	`UISegmentedControl`
`picker().menu()`	`UIButton` + `UIMenu`
`picker().inline()`	`UIStackView` of check-marked buttons
`progress(f)`	`UIProgressView`
`spinner()`	`UIActivityIndicatorView`
`scroll`	`UIScrollView`
`list`	`UITableView` (plain style, recycled cells)
`nav`	`UINavigationController`
`nav_menu`	`UITableView` (inset-grouped)
`tabs`	`UITabBarController`
`cover()`	a full-screen modal `UIViewController`
`image`	`UIImageView`
`canvas`	a custom `UIView` replaying the display list through Core Graphics
dialogs / alerts / prompts	`UIAlertController`
file dialogs	`UIDocumentPickerViewController`
context menus	`UIContextMenuInteraction`
external `activity()`	`UIActivityIndicatorView`
external `search_field()`	`UISearchTextField`
external `date_picker()` / `time_picker()`	`UIDatePicker`
external `pull_refresh()`	`UIRefreshControl`
external `webview()`	`WKWebView`
external `media()`	`AVPlayerViewController`
external `map()`	`MKMapView`
external `lottie()`	`LottieAnimationView` (lottie-ios, via SwiftPM)

Day has no checkbox, radio, stepper or table piece — toggle is the only boolean control, radio behavior is picker().inline(), and list is the only collection.

Text measurement is UIKit’s own sizeThatFits: on the realized view, so wrapping matches what the system would do anywhere else on the platform.