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

lattner

Swift Concurrency Manifesto

Author: Chris Lattner

Chinese Translation by Jason Yu

Contents

• Introduction
• Overall Vision

charlesroper

How to setup a practically free CDN using Backblaze B2 and Cloudflare

⚠️ Note 2023-01-21
Some things have changed since I originally wrote this in 2016. I have updated a few minor details, and the advice is still broadly the same, but there are some new Cloudflare features you can (and should) take advantage of. In particular, pay attention to Trevor Stevens' comment here from 22 January 2022, and Matt Stenson's useful caching advice. In addition, Backblaze, with whom Cloudflare are a Bandwidth Alliance partner, have published their own guide detailing how to use Cloudflare's Web Workers to cache content from B2 private buckets. That is worth reading,

myusuf3

To remove a submodule you need to:

• Delete the relevant section from the .gitmodules file.
• Stage the .gitmodules changes git add .gitmodules
• Delete the relevant section from .git/config.
• Run git rm --cached path_to_submodule (no trailing slash).
• Run rm -rf .git/modules/path_to_submodule (no trailing slash).
• Commit git commit -m "Removed submodule "
• Delete the now untracked submodule files rm -rf path_to_submodule

katylava

Update 2022: git checkout -p <other-branch> is basically a shortcut for all this.

FYI This was written in 2010, though I guess people still find it useful at least as of 2021. I haven't had to do it ever again, so if it goes out of date I probably won't know.

Example: You have a branch refactor that is quite different from master. You can't merge all of the commits, or even every hunk in any single commit or master will break, but you have made a lot of improvements there that you would like to bring over to master.

Note: This will not preserve the original change authors. Only use if necessary, or if you don't mind losing that information, or if you are only merging your own work.

chriseidhof

import SwiftUI

struct SizeKey: PreferenceKey {
    static func reduce(value: inout CGSize?, nextValue: () -> CGSize?) {
        value = value ?? nextValue()
    }
}
struct ContentView: View {
    @State var width: CGFloat? = nil
    var body: some View {

krzyzanowskim

struct ContentView: View {
    @State var color: Color = .Pastel.random()

    var body: some View {
        Rectangle()
            .foregroundColor(color)
            .onTapGesture {
                color = .Pastel.random()
            }
    }

nicklockwood

// This gist demonstrates how you can implement versioning for a Codable struct to support loading
// old serialized data after changing the structure. Notable features of this solution:
//
// * No need to make new properties optional, or to perform post-processing on the struct after
//   loading in ordeer to populate missing values
// * No need to change the call site - from the outside this struct behaves just the same
//   as if we had implemented codable directly in the normal way.
// * Versioning can be applied individually to parents or leaves in a larger tree of
//   structs without affecting the other elements
// * This approach will work even if the original struct was not designed with versioning in mind

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))

DivineDominion

202207041909 AppStorage extension for strongly typed keys

#appstorage #swiftui

The @AppStorage property wrapper for observable access to UserDefaults keys is stringified.

To get a strongly typed key access, I oriented myself on the @Environment(\.keyPath) wrapper and my experience with SwiftyUserDefaults and its subscript-based access.

// Use defaultValue from the key:
@AppStorage(\.showOnboarding) var showOnboarding