ID4

Welcome to ID4, a Swift package describing a 32-bit type identifier, similar to OSType or FourCC.

Usage

The ID4 type encodes four ASCII values, and is often used for identifying types in file IO.

For example, to convert the valus "TEST" into an ID4, the type can be created from a string:

let id4 = ID4("TEST")  // 1413829460

The ID4 can then be converted back into ASCII values for simple debugging:

let id4 = ID4("TEST")  // 1413829460

let a = id4.a  // "T"
let b = id4.b  // "E"
let c = id4.c  // "S"
let d = id4.d  // "T"

Only the first four characters of the string will be used:

ID4("TEST") == ID4("TEST THIS LONG STRING") // True

And short strings will be padded with spaces:

ID4("T") == ID4("T    ")  // True

Initializers are also provided to create ID4 types from individual characters or ASCII values:

ID4(1413829460) == ID4("TEST")  // True
ID4(a: 84, b: 69, c: 83, d: 84) == ID4("TEST")  // True
ID4("T", "E", "S", "T") == ID4("TEST")  // True
ID4(a: "T", b: "E", c: "S", d: "T") == ID4("TEST")  // True
ID4(("T", "E", "S", "T") == ID4("TEST")  // True

As the string could contain non-ASCII types such as unicode characters, the initializer returns an optional ID4. A macro is provided that provides compile time checking of the string to ensure it can be used to create an ID4:

#ID4("TEST")  // Success
#ID4("😢")  // Error

Installation

ID4 is distributed using the Swift Package Manager. To install it within another Swift package, add it as a dependency within your Package.swift manifest:

let package = Package(
    // . . .
    dependencies: [
        .package(url: "https://github.com/mattcox/ID4.git", branch: "main")
    ],
    // . . .
)

If you’d like to use Pack within an application on Apple platforms, then use Xcode’s File > Add Packages... menu command to add it to your project.

Import Pack wherever you’d like to use it:

import ID4