Arek Holko fastred

Thoughts on Swift 2 Errors

When Swift was first announced, I was gratified to see that one of the (few) philosophies that it shared with Objective-C was that exceptions should not be used for control flow, only for highlighting fatal programming errors at development time.

So it came as a surprise to me when Swift 2 brought (What appeared to be) traditional exception handling to the language.

Similarly surprised were the functional Swift programmers, who had put their faith in the Haskell-style approach to error handling, where every function returns an enum (or monad, if you like) containing either a valid result or an error. This seemed like a natural fit for Swift, so why did Apple instead opt for a solution originally designed for clumsy imperative languages?

I'm going to cover three things in this post:

What the hell is a Monad ?

General explanations:

Videos:

Brian Beckman: Don't fear the Monad

carlossless [09:50] So anyone used RxSwift? I’m wondering what are your thoughts and opinions vs RAC3.

jspahrsummers [10:00] @carlossless: https://github.com/ReactiveCocoa/ReactiveCocoa/blob/07813339d3c44aa02fb1b71777baa4ede0f0f77a/README.md#how-does-reactivecocoa-relate-to-rx

carlossless [10:13] Yeah, I was looking for a more practical point of view but even so. RxSwift has UI bindings, it follows the haskell naming for most transformation and composition functions map, filter etc. rather than select, where.

carlossless [10:14]

LLDB Debugging Cheat Sheet

Commands

LLDB Commands

LLDB comes with a great set of commands for powerful debugging.

help

Your starting point for anything. Type help to get a list of all commands, plus any user installed ones. Type 'help for more information on a command. Type help to get help for a specific option in a command too.

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).

	#!/usr/bin/env bash

	# If your OS X WiFi connection stops working, but can be fixed by
	# toggling WiFi off and then on, this script can help prevent mouse arm.
	# Pings Apple's server repeatedly, toggling WiFi off/on when a connection times out.
	while true ; do
	curl --head --silent --connect-timeout 10 http://www.apple.com/my-wifi-keeps-dropping-out > /dev/null
	if [ $? -ne 0 ] ; then
	networksetup -setairportpower en1 off
	networksetup -setairportpower en1 on

	import Swift

	/*:
	A simple type-erased sequence
	*/
	let seq = AnySequence([1,2,3])


	/*:
	## Who Needs Types Like That?

	//
	// Signal+Extensions.swift
	// Khan Academy
	//
	// Created by Nacho Soto on 10/1/15.
	// Copyright © 2015 Khan Academy. All rights reserved.
	//

	import ReactiveCocoa

	# The trick is to link the DeviceSupport folder from the beta to the stable version.
	# sudo needed if you run the Mac App Store version. Always download the dmg instead... you'll thank me later :)

	# Support iOS 15 devices (Xcode 13.0) with Xcode 12.5:
	sudo ln -s /Applications/Xcode-beta.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/15.0 /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport

	# Then restart Xcode and reconnect your devices. You will need to do that for every beta of future iOS versions

	# (A similar approach works for older versions too, just change the version number after DeviceSupport)

	As of iOS 11/macOS High Sierra, and only including ones in Foundation and CoreFoundation

	Strings:

	_NSCFString - a CFStringRef or CFMutableStringRef. This is the most common type of string object currently.
	- May have 8 bit (ASCII) or 16 bit (UTF-16) backing store
	_NSCFConstantString - a compile time constant CFStringRef, like you'd get with @"foo"
	- May also be generated by dynamic string creation if matches a string in a pre-baked table of common strings called the StringROM
	NSBigMutableString - an NSString backed by a CFStorage (https://github.com/opensource-apple/CF/blob/master/CFStorage.h) for faster handling of very large strings
	NSCheapMutableString - a very limited NSMutableString that allows for zero-copy initialization. Used in NSFileManager for temporarily wrapping stack buffers.