oleganza

Async semantics proposal for Swift

Modern Cocoa development involves a lot of asynchronous programming using blocks and NSOperations. A lot of APIs are exposing blocks and they are more natural to write a lot of logic, so we'll only focus on block-based APIs.

Block-based APIs are hard to use when number of operations grows and dependencies between them become more complicated. In this paper I introduce asynchronous semantics and Promise type to Swift language (borrowing ideas from design of throw-try-catch and optionals). Functions can opt-in to become async, programmer can compose complex logic involving asynchronous operations while compiler produces necessary closures to implement that logic. This proposal does not propose new runtime model, nor "actors" or "coroutines".

Table of contents

claybridges

#!/bin/bash --login

# Cf. http://stackoverflow.com/questions/33041109
#
# Xcode 7 (incl. 7.0.1) seems to have a dependency on the system ruby.
# xcodebuild is screwed up by using rvm to map to another non-system
# ruby†. This script is a fix that allows you call xcodebuild in a
# "safe" rvm environment, but will not (AFAIK) affect the "external"
# rvm setting.
#

brandonstephens

{% assign url_split = page.url | replace_first: "/" | split:"/" %} 
{% assign url_size = url_split.size %}

<ol class="breadcrumb">
  {% if url_size < 1 %}
    <li class="active">Home</li>
  {% else %}
    <li><a href="/">Home</a></li>
  {% endif %}

lattner

Async/Await for Swift

• Proposal: SE-XXXX
• Authors: Chris Lattner, Joe Groff

Introduction

Modern Cocoa development involves a lot of asynchronous programming using closures and completion handlers, but these APIs are hard to use. This gets particularly problematic when many asynchronous operations are used, error handling is required, or control flow between asynchronous calls gets complicated. This proposal describes a language extension to make this a lot more natural and less error prone.

This paper introduces a first class Coroutine model to Swift. Functions can opt into to being async, allowing the programmer to compose complex logic involving asynchronous operations, leaving the compiler in charge of producing the necessary closures and state machines to implement that logic.

smileyborg

// UICollectionView Objective-C example

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
        
    NSIndexPath *selectedIndexPath = [[self.collectionView indexPathsForSelectedItems] firstObject];
    if (selectedIndexPath != nil) {
        id<UIViewControllerTransitionCoordinator> coordinator = self.transitionCoordinator;
        if (coordinator != nil) {
            [coordinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext> context) {

ryanashcraft

struct Memoized<A: Equatable, R> {
    typealias Value = (_ params: A) -> R
    var callback: Value
    @XState private var prevParam: A? = nil
    @XState private var prevValue: R? = nil

    init(_ callback: @escaping Value) {
        self.callback = callback
    }

Daniel-ltw

name: Build Artifacts

on: [push]

jobs:
  build:

    runs-on: ubuntu-latest

    steps:

chriseidhof

// Run any SwiftUI view as a Mac app.

import Cocoa
import SwiftUI

NSApplication.shared.run {
    VStack {
        Text("Hello, World")
        	.padding()
            .background(Capsule().fill(Color.blue))

Clarko

//
//  ConvenientColors.swift
//
//  Created by Clarko on 7/15/20.
//
//  Color.primary and Color.secondary are great for foreground text
//  that adapts in light & dark mode, but there are a lot more
//  UI Element Colors in iOS and macOS:
//
//  https://developer.apple.com/documentation/uikit/uicolor/ui_element_colors

steipete

//
//  KeyCommand.swift
//  Adds Keyboard Shortcuts to SwiftUI on iOS 13
//  See https://steipete.com/posts/fixing-keyboardshortcut-in-swiftui/
//  License: MIT
//
// Usage: (wrap view in `KeyboardEnabledHostingController`)
// Button(action: {
//       print("Button Tapped!!")
//  }) {