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

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,

robflaherty

<?php
/*
 * Converts CSV to JSON
 * Example uses Google Spreadsheet CSV feed
 * csvToArray function I think I found on php.net
 */

header('Content-type: application/json');

// Set your CSV feed

nicklockwood

/// Withable is a simple protocol to make constructing
/// and modifying objects with multiple properties
/// more pleasant (functional, chainable, point-free)
public protocol Withable {
  init()
}

public extension Withable {
  /// Construct a new instance, setting an arbitrary subset of properties
  init(with config: (inout Self) -> Void) {

nfarina

#import <UIKit/UIKit.h>

@interface UIView (SMFrameAdditions)

@property (nonatomic, assign) CGPoint $origin;
@property (nonatomic, assign) CGSize $size;
@property (nonatomic, assign) CGFloat $x, $y, $width, $height; // normal rect properties
@property (nonatomic, assign) CGFloat $left, $top, $right, $bottom; // these will stretch the rect

@end

mackuba

Following the tradition from last year, here's my complete list of all interesting features and updates I could find in Apple's OSes, SDKs and developer tools that were announced at this year's WWDC. This is based on the keynotes, the "What's New In ..." presentations and some others, Apple's release notes, and blog posts and tweets that I came across in the last few weeks.

If for some reason you haven't watched the talks yet, I really recommend watching at least the "State of the Union" and the "What's New In" intros for the platforms you're interested in. The unofficial WWDC Mac app is great way to download the videos and keep track of what you've already watched.

If you're interested, here are my WWDC 2015 notes (might be useful if you're planning to drop support for iOS 8 now and start using some iOS 9 APIs).

---

OSX → macOS 10.12 Sierra

Ashton-W

<?xml version="1.0" encoding="UTF-8"?>
<Bucket
   type = "2"
   version = "2.0">
   <Breakpoints>

      <!-- All Exceptions -->
      <BreakpointProxy
         BreakpointExtensionID = "Xcode.Breakpoint.ExceptionBreakpoint">
         <BreakpointContent

calebd

extension Array {
    
    func first() -> Element? {
        if isEmpty {
            return nil
        }
        return self[0]
    }
    
    func last() -> Element? {

numo16

#define ApplicationDelegate                 ((AppDelegate *)[[UIApplication sharedApplication] delegate])
#define UserDefaults                        [NSUserDefaults standardUserDefaults]
#define NotificationCenter                  [NSNotificationCenter defaultCenter]
#define SharedApplication                   [UIApplication sharedApplication]
#define Bundle                              [NSBundle mainBundle]
#define MainScreen                          [UIScreen mainScreen]
#define ShowNetworkActivityIndicator()      [UIApplication sharedApplication].networkActivityIndicatorVisible = YES
#define HideNetworkActivityIndicator()      [UIApplication sharedApplication].networkActivityIndicatorVisible = NO
#define NetworkActivityIndicatorVisible(x)  [UIApplication sharedApplication].networkActivityIndicatorVisible = x
#define NavBar                              self.navigationController.navigationBar

lsavino

DEPRECATED for Xcode 10 🎈

(check out What's New in Swift at 11:40, slide 42)

Whole Module Compilation Optimizations: Why these terms are sometimes misleading

When you look up how to compile swift faster for debug builds, people very earnestly give advice that seems contradictory: you should "try using the whole module optimization flag," and also "never use whole module optimization for debugging". [^1]

This is confusing because some of us are using these two general words:

compilation: "turning text into an executable program"