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Wilfa Svart BLE Scale Protocol Documentation

This document outlines the Bluetooth Low Energy (BLE) protocol for communicating with Wilfa Svart Uni Scale devices, specifically the Gen 1 and Gen 2 models. The implementation is reverse-engineered from official firmware behavior and the Android application.

Overview

The Wilfa Svart scale exposes BLE services and characteristics for:

• Receiving weight data
• Monitoring unit changes and other state updates
• Sending commands (e.g., tare, change unit)

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import OrderedCollections

protocol HasCacheCost {
    var cacheCost: Int { get }
}

extension HasCacheCost {
    var cacheCost: Int {
        type(of: self) == AnyObject.self ? 0 : MemoryLayout.size(ofValue: self)
    }

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import Foundation

extension Result: Codable where Success: Codable, Failure: Codable {

    public init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        switch try container.decode(ResultType.self, forKey: .type) {
        case .success:
            self = .success(try container.decode(Success.self, forKey: .value))
        case .failure:

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import Foundation

class AutoId {
    private init() {}

    static func newId() -> String {
        // Alphanumeric characters
        let chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
        // The largest byte value that is a multiple of `char.length`.
        let maxMultiple = Int(256 / chars.count) * chars.count

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import Foundation

@propertyWrapper
struct Injected<T> {
    private let keyPath: WritableKeyPath<InjectedValues, T>

    var wrappedValue: T {
        get { InjectedValues[keyPath] }
        set { InjectedValues[keyPath] = newValue }
    }

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import Foundation

protocol AppendOnlyDatabaseProtocol {
    var count: Int { get }

    mutating func append(_ other: Data)

    subscript(index: Data.Index) -> UInt8 { get }
    subscript(bounds: Range<Data.Index>) -> Data { get }
}

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• I am ts95 on github.
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To claim this, I am signing this object:

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import Foundation
import CoreLocation

// based on https://gis.stackexchange.com/a/18740

extension CLLocationCoordinate2D {
    var cartesian: CartesianCoordinate3D { .init(from: self) }

    // Returns the coordinates of the midpoint between point a and b.
    // Limitation: point a and b may not be diametrically opposite.

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#!/bin/bash

# Parameters
source="$(pwd)/"                            # Track folder source where diffs are checked
project_root=${0%/*}                        # Track project root folder
swiftlint_path='swiftlint'                  # Track SwiftLint path

changed_files () {
  sort -u \
    <(git diff --name-only --diff-filter=d --cached) \

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import SwiftUI
import MapKit

extension Map {

    init<Items>(
        coordinateRegion: Binding<MKCoordinateRegion>,
        interactionModes: MapInteractionModes = .all,
        showsUserLocation: Bool = false,
        userTrackingMode: Binding<MapUserTrackingMode>? = nil,