rnapier

// Built with Swift 6 (Xcode 16b1)
actor Accumulator {
    static let shared = Accumulator()

    var values: [String] = []

    // A couple of approaches, neither of which works.
    func add(value: String) { values.append(value) }

    nonisolated func addSync(value: String) { Task { await add(value: value) } }

rnapier

// Version of Swift 6 Mutex, with minimal API (just withLock), portable to at least iOS 15, probably much earlier.
// I cannot yet promise it's actually correct.

@frozen
public struct Mutex<Value> {
    private let buffer: ManagedBuffer<Value, os_unfair_lock>

    public init(_ initialValue: Value) {
        buffer = ManagedBuffer<Value, os_unfair_lock>.create(minimumCapacity: 1) { _ in initialValue }
        buffer.withUnsafeMutablePointerToElements { lockPtr in

rnapier

// In regards to https://mastodon.social/@mattiem/112285978801305971

// MainActor class with synchronous methods
@MainActor final class M {
    func methodA() {}
    func methodB() {}
}

// Actor that relies on M.
actor A {

rnapier

/// Some exploration into how selector-based notification interact with actors.
///
/// Or in the words of Brent Simmons (@[email protected]),
/// "Selector-based Notification Observers Are Actually Good"

/// Overall, I'm reasonably convinced, in that it avoids the headaches of `deinit` in actors.
/// However, Combine-based observation is also good at this, so I don't yet have a strong opinion
/// about old-school selectors vs Combine beyond my usual nervousness around Combine.
/// Whether "I'd like to reduce Combine" is more or less powerful than "I'd like to reduce @objc"
/// is yet to be seen.

rnapier

// With Strict Concurrency

class C {}

struct S {
    func f() {
        Task { // Surprisingly need `@MainActor in` here to make this correct
            await g() // Warning: Passing argument of non-sendable type 'C' into main actor-isolated context may introduce data races
        }
    }

rnapier

// Demonstration of FB12811151
// On some devices (so far we haven't found any newer than an 2020 SE2), VoiceOver will allow you to select
// the link by swiping down, and then will immediately re-select the entire text. The user generally cannot
// follow the link because it snaps back too quickly.
//
// On one iPhone 8, this did not reproduce until the device went to sleep, then it reliably reproduced.

import SwiftUI

let text = try! AttributedString(markdown: "Here is a link to [ArchiveOrg](https://archive.org). It should be selectable with the rotor without jumping back to the whole text.")

rnapier

import Foundation

public class Disposable {
    private var isDisposed = false
    private let _dispose: () -> Void
    public func dispose() {
        if !isDisposed {
            _dispose()
            isDisposed = true
        }

rnapier

// This GridView makes me cry. It is recreating an HTML-style bordered table, sized to
// its data, with a header. It requires a GeometryReader and Preferences, which might
// be unavoidable, but it also requires a *horrible* DispatchQueue.main.async in updateMaxValue.
// This means it doesn't work in Previews, and completely breaks the idea of "declarative" UI.

import SwiftUI

struct WidthPreferenceKey: PreferenceKey {
    static var defaultValue: CGFloat = .zero
    static func reduce(value: inout CGFloat, nextValue: () -> CGFloat) {

rnapier

struct LengthLimitedTextField: UIViewRepresentable  {
    var title: String
    @Binding var text: String
    var maxLength: Int
    var onCommit: () -> Void

    init(_ title: String, text: Binding<String>, maxLength: Int = 255, onCommit: @escaping () -> Void) {
        self.title = title
        self._text = text
        self.maxLength = maxLength

rnapier

// Based on https://twitter.com/ravibastola/status/1249555595285291008?s=20

extension Bundle {
    // This is synchronous, which is bad if called on the main queue.
    func decodeJSON<T: Decodable>(_ type: T.Type = T.self, from filename: String) throws -> T {
        guard let path = self.url(forResource: filename, withExtension: nil) else {
            throw NSError(domain: NSCocoaErrorDomain,
                          code: CocoaError.fileNoSuchFile.rawValue,
                          userInfo: [NSFilePathErrorKey: filename])
        }