BezelKit — Generator

Perfecting Corners, One Radius at a Time

Overview

The Generator is a Swift CLI tool that extracts device bezel (corner radius) data from iOS Simulators and writes the results into the BezelKit package resource.

It uses a SwiftUI app (FetchBezel) that reads the private UIScreen._displayCornerRadius API from within a simulator — keeping the public-facing package completely free of private API usage.

Requirements

• macOS 13 or later
• Xcode with at least one iOS Simulator runtime installed
• Swift 5.10+

Pure Swift — no external toolchain required.

Building

From the Generator/ directory:

swift build

Dependencies are resolved automatically on first build.

Usage

Run from the Generator/ directory of the BezelKit repo:

swift run BezelGenerator

This processes any devices listed in pending inside apple-device-database.json, boots the corresponding simulators, captures their bezel values, and updates both the cache database and the minified package resource.

Subcommands

Command	Description
generate (default)	Process pending devices and update the database
generate-docs	Regenerate SupportedDeviceList.md from bezel.min.json
test	Test the full pipeline on one simulator without touching the database

---

generate — process pending devices

swift run BezelGenerator
# or explicitly:
swift run BezelGenerator generate

Option	Default	Description
--database	./apple-device-database.json	Path to the device database JSON
--project	./FetchBezel/FetchBezel.xcodeproj	Path to the FetchBezel Xcode project
--scheme	FetchBezel	Xcode scheme name
--bundle-id / -b	com.markbattistella.FetchBezel	App bundle ID
--output	../Sources/BezelKit/Resources/bezel.min.json	Output path for the minified resource
--app-output	./output	Xcode build output directory
--verbose / --no-verbose	enabled	Toggle terminal output

---

test — verify the pipeline without modifying the database

swift run BezelGenerator test --name "iPhone 16 Pro"

Boots the named simulator, reads its bezel value, and tears everything down — without reading or writing apple-device-database.json. Use this to verify the pipeline works for a specific device before adding it to pending.

Option	Default	Description
--name / -n	(required)	Simulator display name to test
--project, --scheme, --bundle-id, --app-output	(same as generate)	Same options as generate

---

generate-docs — regenerate the supported device list

swift run BezelGenerator generate-docs

Reads bezel.min.json and writes SupportedDeviceList.md in the repo root. This is also called automatically by the pre-push git hook.

Option	Default	Description
--input	../Sources/BezelKit/Resources/bezel.min.json	Path to the minified JSON
--output	../SupportedDeviceList.md	Output path for the markdown file

---

Database Structure

All device data lives in apple-device-database.json:

{
  "_metadata": { "Author": "...", "Project": "...", "Website": "..." },
  "devices": {
    "iPad":   { "iPad16,1":   { "bezel": 21.5, "name": "iPad mini (A17 Pro)" } },
    "iPhone": { "iPhone17,1": { "bezel": 62,   "name": "iPhone 16 Pro" } },
    "iPod":   {}
  },
  "pending": {
    "iPhone18,1": { "name": "iPhone 17 Pro" }
  },
  "problematic": {}
}

Section	Purpose
devices	Processed devices with confirmed bezel values, split by iPad, iPhone, and iPod
pending	Devices queued for processing on the next generate run
problematic	Devices that could not be processed (no simulator runtime available); automatically retried on every run

Adding new devices

1. Add the device identifier and its simulator display name to pending in apple-device-database.json:

   "pending": {
     "iPhone18,1": { "name": "iPhone 17 Pro" }
   }

   The name must match the Device Type shown in Xcode's Create New Simulator screen.

   

2. Run the generator:

   swift run BezelGenerator

Identifiers that share the same simulator name (e.g. Wi-Fi and Cellular variants) are grouped and processed in a single simulator boot — the bezel value is written to all matching identifiers automatically.

Success and failure

Outcome	Result
Simulator boots and returns data	Entry moves from pending → devices with the captured bezel value
No runtime available for the device	Entry moves from pending → problematic; retried automatically on future runs

Contributing

Contributions are welcome. If you find a bug or want to add device support, please open an issue or pull request.

Note

Pull request titles must follow this format:

YYYY-mm-dd - {title}
eg. 2025-03-01 - Add iPhone 17 series

Licence

Released under the MIT licence. See LICENCE for details.