andymatuschak

A composable pattern for pure state machines with effects

State machines are everywhere in interactive systems, but they're rarely defined clearly and explicitly. Given some big blob of code including implicit state machines, which transitions are possible and under what conditions? What effects take place on what transitions?

There are existing design patterns for state machines, but all the patterns I've seen complect side effects with the structure of the state machine itself. Instances of these patterns are difficult to test without mocking, and they end up with more dependencies. Worse, the classic patterns compose poorly: hierarchical state machines are typically not straightforward extensions. The functional programming world has solutions, but they don't transpose neatly enough to be broadly usable in mainstream languages.

Here I present a composable pattern for pure state machiness with effects,

trilliwon

// Swift4
let image = UIImage(named: "sample")
let data = image?.pngData()
let data = image?.jpegData(compressionQuality: 0.9)
let uiImage: UIImage = UIImage(data: imageData)

// deprecated
// var imageData: Data = UIImagePNGRepresentation(image)

saoudrizwan

import UIKit

class ResponsiveView: UIView {
    override var canBecomeFirstResponder: Bool {
        return true
    }
}

class ViewController: UIViewController {
    

NeilsUltimateLab

Understanding UIViewController Rotation

Problem

To enable the rotation of a single view controller used to display the preview of Images/Videos. It is intuitive to allow user to rotate there device and screen changes accordingly, so it feels pleasant. But to achieve this, we need to enable the (almost) all Supported Device orientations.

Ex: `Portrait`, `LandscapeLeft`, `LandscapeRight`.

keima

import android.os.Bundle
import android.util.Log
import android.view.ViewGroup
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import androidx.databinding.DataBindingUtil
import androidx.lifecycle.Lifecycle
import androidx.lifecycle.LifecycleObserver
import androidx.lifecycle.OnLifecycleEvent
import app.keima.android.recyclerviewsandbox.databinding.ActivityMainBinding

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

N5-bots

//
//  WKCookieWebView.swift
//
//  Created by Jens Reynders on 30/03/2018.
//  Copyright (c) 2018 November Five
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

atomicbird

/// Log the current filename and function, with an optional extra message. Call this with no arguments to simply print the current file and function. Log messages will include an Emoji selected from a list in the function, based on the hash of the filename, to make it easier to see which file a message comes from.
/// - Parameter message: Optional message to include
///   - file: Don't use; Swift will fill in the file name
///   - function: Don't use, Swift will fill in the function name
///   - line: Don't use, Swift will fill in the line number
func logMilestone(_ message: String? = nil, file: String = #file, function: String = #function, line: Int = #line) -> Void {
    #if DEBUG
    // Feel free to change the list of Emojis, but don't make it shorter, because a longer list is better.
    let logEmojis = ["😀","😎","😱","😈","👺","👽","👾","🤖","🎃","👍","👁","🧠","🎒","🧤","🐶","🐱","🐭","🐹","🦊","🐻","🐨","🐵","🦄","🦋","🌈","🔥","💥","⭐️","🍉","🥝","🌽","🍔","🍿","🎹","🎁","❤️","🧡","💛","💚","💙","💜","🔔"]
    let logEmoji = logEmojis[abs(

arkivanov

class FragmentWithDialog(output: (Output) -> Unit) : Fragment() {

    sealed class Output {
        object DialogShown : Output()
    }
}

class FragmentWithInput(input: Observable<Input>) : Fragment() {

    sealed class Input {

BetterProgramming

extension UIView {
    func dropShadow() {
        self.layer.shadowColor = UIColor.gray.cgColor 
        self.layer.shadowOpacity = 0.3
        self.layer.shadowOffset = CGSize(width: 2, height: 4)
        self.layer.shadowRadius = 5
    }
}