ole

// Make sure both the string and the substring are larger than 15 UTF-8 bytes
// to avoid the small string optimization
var str = "Hello world 1 Hello world 2 Hello world 3 Hello world 4 Hello world 5 Hello world 6 Hello world 7 Hello world 8 Hello world 9"
let prefixToStrip = 14
var substr = str.dropFirst(prefixToStrip).prefix(27)
let strToAppend = "+++APPENDED+++"

// ⚠️ It makes a difference how you mutate the Substring:
// - substr.append → Apparently makes a copy of the entire original string
//   *and* even shifts the original string contents back to make room,

ole

#!/bin/zsh

# Test if the Swift compiler knows about a particular language feature.
#
# Usage:
#
#     swift-has-feature [--swift SWIFT_PATH] FEATURE
#
# The exit code signals success (= the compiler knows this feature) or failure.
#

ole

import SwiftUI

@main
struct GroupWithTaskApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}

ole

import Foundation

/// An "extension" of FloatingPointFormatStyle that adds a `minusSign` API to customize
/// the character(s) used as the minus sign.
///
/// You could add additional extensions by following the same pattern.
///
/// All other APIs are copied from FloatingPointFormatStyle and forward to it for their
/// implementation. This isn’t a full replica of the FloatingPointFormatStyle API, though,
/// because it’s only intended as a proof of concept.

ole

import Foundation

extension FormatStyle {
    static func ordinal<FormatInput: BinaryInteger>() -> OrdinalFormatStyle<FormatInput>
        where Self == OrdinalFormatStyle<FormatInput>
    {
        OrdinalFormatStyle()
    }
}

ole

Warren Moore – Thirty Days of Metal

Great series of short articles introducing Apple's Metal framework.

• 2022-04-01: Day 1: Devices
• 2022-04-02: Day 2: Buffers
• 2022-04-03: Day 3: Commands
• 2022-04-04: Day 4: MTKView
• 2022-04-05: Day 5: Shaders
• 2022-04-06: Day 6: Pipelines

ole

import SwiftUI

struct ContentView: View {
    var body: some View {
        VStack {
            FrameworkView1 {
                Text("FrameworkView1")
            }
            .border(.red)

ole

// UserDefaults KVO observation with AsyncSequence/AsyncStream
// Ole Begemann, 2023-04
// https://gist.github.com/ole/fc5c1f4c763d28d9ba70940512e81916

import Foundation

extension UserDefaults {
    func observeKey<Value>(_ key: String, valueType _: Value.Type) -> AsyncStream<Value?> {
        var continuation: AsyncStream<Value?>.Continuation? = nil
        let stream = AsyncStream(Value?.self) {

ole

import SwiftUI

extension View {
    /// Proposes a percentage of its received proposed size to `self`.
    ///
    /// This modifier multiplies the proposed size it receives from its parent
    /// with the given factors for width and height.
    ///
    /// If the parent proposes `nil` or `.infinity` to us in any dimension,
    /// we’ll forward these values to our child view unchanged.

ole

struct MyError: Error {}

func fireAndForget() async {
    await withThrowingTaskGroup(of: Void.self) { group in
        group.addTask {
            print("child task start")
            print("child task throws")
            throw MyError()
        }
        // Notice that we're not awaiting the child task.