Writing Command Line Tools in Swift Using ArgumentParser, Part 4: Customizing Help
In the past few weeks, we have explored how to use ArgumentParser and many of its features. It’s great that ArgumentParser provides a lot of functionality for free, but it wouldn’t make sense to build great tools that users can’t figure out how to use. This week is all about that.
We saw how ArgumentParser can build a lot of documentation for free, but we can actually do more. This week, we will explore how we can improve the documentation generated for our command line tools.
Last week we explored how we can build a simple command line tool. We learned how to use @Argument, @Option, and @Flag as the building blocks for ArgumentParser command line tools. We we saw last week was enough to build many simple tools, but there’s still a lot to explore, and cool things to learn.
This week we will learn about input validation and errors, so we can build better tools that take more constrained parameters when relevant.
A few weeks ago, the Swift project introduced the ArgumentParser package. This package makes it easy to write command line tools by providing automatic parsing, documentation generation, and more.
In this article, we will explore ArgumentParser, and how we can start building some command line tools with it, using the basic building blocks, which are three Property Wrappers called Argument, Option, and Flag.
Project Configuration
Open Xcode and create a new project of type “Command Line Tool”. You cannot use this project type for iOS/iPadOS, so if you don’t find it, head over to the Mac tab.
WWDC2020 is just around the corner*, and it hasn’t been one year since WWDC2019 took place. There is still a lot of ground to cover regarding the new tools and APIs demonstrated then. and In this article we will focus on a feature new to Swift itself: Function Builders.
*: Maybe. :(
If you have been hacking away at SwiftUI, you have probably been wondering how it makes it possible to build great UIs with very nice syntactic sugar. Other than property wrappers, SwiftUI is also possible thanks to Function Builders. In this article, we will briefly mention how SwiftUI uses Function Builders, and later we will create our own function builders that have nothing not do with SwiftUI. This way, it will become evident why Function Builders are really neat, and why they don’t have to be strictly tied to SwiftUI.
There may be cases in which you need to find related words to others. With the NSLEmbedding class, you can find related strings based on the proximity of their vectors.
Using NLEmbedding
Using NLEmbedding is very straight forward. A simple task is to get an array of related words, which come as an array of (String, NLDistance) back.
The distance between words tells you how “related” they are
In the past few weeks, we have explored how we can tokenize natural language text and how to recognize the language a natural language text is written in. This week we will continue exploring more natural language APIs provided by the NaturalLanguage framework. We will learn about the NLTagger class, which allows us to to analyze natural language text to find parts of speech, lexical classes, lemma, scripts, and more. This API, introduced in iOS 12, implements machine learning to work, and just like the other NaturalLanguage classes, is very easy to use.
Continuing my trend of writing about language processing, today I want to discuss about identifying the language of a body of text. This is an interesting task we can do thanks, once again, to Apple’s investment in APIs linked to machine learning.
Today we will explore the NLLanguageRecognizer object. Introduced in iOS 12, this class can do a lot of language recognizing, from detecting the “dominant language” of a string, to all the possible languages.
Working with Natural Language is possible thanks to machine learning. Starting on iOS 12, Apple has provided many APIs just for this task. In this article we will explore how to use NLTokenizer to separate natural language text into its proper units.
Introduction to Natural Language Tokenizing
If you are not familiar with the inner workings of Natural Language processing, tokenizing simply means that we separate a string and analyze it to find its semantic units. If you are writing a program that processes text, you may be tempted to split the string using a separator. For example, if you wanted to get all the words in a natural sentence string in an array, you would write something like this:
iOS has a lot of APIs that deal with natural language detection. One such class is NSDataDetector. This class allows you to match different kinds of data in text, including dates, time, links, and more. This class, actually introduced a very long time ago (in the iOS 4.0 days!) makes it very easy to find this kind of data in strings. In this article we will explore how to use this very old class - whose documentation is Objective-C only at this time - in Swift, and how to do common tasks with it.