# SingleValueCodable

### A simple exercise in leverage

October 24, 2017

The new Codable protocol is flexible enough to allow a different encoded representation from the in-memory representation which is a nice property to have in a serialization mechanism. Today I'm going to build SingleValueCodable to automate that work when dealing with RawRepresentable types.

# The Setup

I want to encode . . .

# AMD System V ABI Reference

July 18, 2017

An ABI reference for quick lookup. If you crash or just want to step through disassembly, check the contents of the registers to see where parameters are being passed.

Arg Register Notes
1 RDI Usually self or address to hold return value
2 RSI Usually _cmd but may . . .

# MemoryLayout

### Size & Stride

June 16, 2017

A quick word of warning to those of you using UnsafePointer and MemoryLayout.

• The size of a type tells you how many bytes it takes to hold that type in memory.
• The stride of a type tells you how far apart each instance of the type is in memory.

If you are doing pointer arithmetic on UnsafePointer then Swift . . .

# Swift REPL Targets

January 22, 2017

Have you seen the message error: repl.swift:2:31: error: '<type>' is only available on OS X <version> or newer? In current releases of Xcode, the Swift REPL uses a hard-coded 10.9 target instead of the current OS.

The solution is fairly easy:

xcrun swift -target x86_64-apple-macosx10.12

. . .

# Improving Optionals

### All problems can be solved by adding another protocol

January 19, 2017

Optionals are great. I've tracked down too many bugs to Objective-C's magical "messages to nil return nil"; I have no interest in going back.

But sometimes there are things you want to do with optionals or when optionals are of a specific type. Here are some of my favorites:

Sometimes . . .

# Quick: Easy DispatchTime

### Expressin' me some literals

November 10, 2016

Here's a quick bonus post. I find using DispatchTime a bit less convenient than it should be. In a GUI application I almost always just want to specify a TimeInterval, aka number of whole or fractional seconds.

Thankfully Swift extensions can grant my heart's desire:

extension DispatchTime: ExpressibleByIntegerLiteral { . . .

# Mixing Initializers

### init? init! init throws

November 09, 2016

Today is a really simple post but something people struggle with, often in the context of extensions or interacting with RawRepresentable enums.

## Can't delegate to failable initializer

Let's say you have a type with a failable initializer. Now you want to extend that type to support deserializing from JSON. You throw . . .