ddunbar

New Build System Tricks

Command Line

alias xcbuild=$(xcode-select -p)/../SharedFrameworks/XCBuild.framework/Versions/A/Support/xcbuild
# THIS DOESNT WORK YET: xcbuild openIDEConsole  # … then switch to Xcode ➡️
xcbuild showSpecs
xcbuild build <foo.pif> [—target <target>]

lattner

Swift Concurrency Manifesto

Author: Chris Lattner

Chinese Translation by Jason Yu

Contents

• Introduction
• Overall Vision

modocache

===-------------------------------------------------------------------------===
                               Swift compilation
===-------------------------------------------------------------------------===
  Total Execution Time: 0.0307 seconds (0.1196 wall clock)

   ---User Time---   --System Time--   --User+System--   ---Wall Time---  --- Name ---
   0.0043 ( 39.3%)   0.0091 ( 45.6%)   0.0133 ( 43.4%)   0.0547 ( 45.7%)  performSema
   0.0030 ( 27.5%)   0.0070 ( 35.2%)   0.0100 ( 32.5%)   0.0437 ( 36.5%)  performSema-loadStdlib
   0.0011 ( 10.0%)   0.0011 (  5.4%)   0.0022 (  7.0%)   0.0081 (  6.7%)  performSema-parseAndCheckTypes
   0.0008 (  7.0%)   0.0009 (  4.4%)   0.0016 (  5.3%)   0.0067 (  5.6%)  Type checking / Semantic analysis

timvisee

Falsehoods programmers believe about time

This is a compiled list of falsehoods programmers tend to believe about working with time.

Don't re-invent a date time library yourself. If you think you understand everything about time, you're probably doing it wrong.

Falsehoods

• There are always 24 hours in a day.
• February is always 28 days long.
• Any 24-hour period will always begin and end in the same day (or week, or month).

tclementdev

libdispatch efficiency tips

The libdispatch is one of the most misused API due to the way it was presented to us when it was introduced and for many years after that, and due to the confusing documentation and API. This page is a compilation of important things to know if you're going to use this library. Many references are available at the end of this document pointing to comments from Apple's very own libdispatch maintainer (Pierre Habouzit).

My take-aways are:

• You should create very few, long-lived, well-defined queues. These queues should be seen as execution contexts in your program (gui, background work, ...) that benefit from executing in parallel. An important thing to note is that if these queues are all active at once, you will get as many threads running. In most apps, you probably do not need to create more than 3 or 4 queues.

• Go serial first, and as you find performance bottle necks, measure why, and if concurrency helps, apply with care, always validating under system pressure. Reuse

mayoff

// See https://stackoverflow.com/q/59367202/77567

import Combine
import Foundation

extension Publisher {
    func step(with stepper: @escaping (SteppingSubscriber<Output, Failure>.Event) -> ()) -> AnyCancellable {
        let subscriber = SteppingSubscriber<Output, Failure>(stepper: stepper)
        self.subscribe(subscriber)
        return .init(subscriber)