# Playgrounds

Published articles for Playgrounds.

This is one page of public article previews, not the complete archive. Follow Next page to continue. Summaries are not the original full articles.

## Swift Type Constrained Extensions: Express Yourself

DevFeed: [Swift Type Constrained Extensions: Express Yourself](<https://devfeed.tech/articles/swift-type-constrained-extensions-express-yourself-37509.md>)

Original publisher: [Read original article](<https://www.cimgf.com/2015/12/14/swift-type-constrained-extensions-express-yourself/>)

Author: Matt Long

Published: 2015-12-14T18:19:55Z

Content type: tutorial

Language: en

Sources: [Cocoa Is My Girlfriend](<https://devfeed.tech/sources/cocoa-is-my-girlfriend.md>)

Topics: [Swift](<https://devfeed.tech/topics/swift.md>), [Objective-C](<https://devfeed.tech/topics/objective-c.md>), [Code](<https://devfeed.tech/topics/code.md>), [Mobile](<https://devfeed.tech/topics/mobile.md>), [JSON](<https://devfeed.tech/topics/json.md>)

Tags: [code](<https://devfeed.tech/tags/code.md>), [coding-practice](<https://devfeed.tech/tags/coding-practice.md>), [fetch](<https://devfeed.tech/tags/fetch.md>), [intermediate](<https://devfeed.tech/tags/intermediate.md>), [json](<https://devfeed.tech/tags/json.md>), [mobile](<https://devfeed.tech/tags/mobile.md>), [objective-c](<https://devfeed.tech/tags/objective-c.md>), [playgrounds](<https://devfeed.tech/tags/playgrounds.md>), [swift](<https://devfeed.tech/tags/swift.md>), [type](<https://devfeed.tech/tags/type.md>), [type-safety](<https://devfeed.tech/tags/type-safety.md>)

### AI overview

This tutorial explains Swift type-constrained extensions, comparing them with Objective-C categories and showing how they can provide type-safe functions and app-specific functionality for arrays and JSON-derived data.

### Source excerpt

I admit it. I was pretty down when Swift was announced. I appreciated the finer points of the reasons for it, however, they weren't convincing-at least not to me-not at first. I denied that it was actually "expressive" as the overall community was referring to it, however, that was before version 2. It's at the [...]

## Swift and valueForKeyPath: You Can't Keep A Good API Down!

DevFeed: [Swift and valueForKeyPath: You Can't Keep A Good API Down!](<https://devfeed.tech/articles/swift-and-valueforkeypath-you-can-t-keep-a-good-api-down-37501.md>)

Original publisher: [Read original article](<https://www.cimgf.com/2014/11/05/swift-and-valueforkeypath-you-cant-keep-a-good-api-down/>)

Author: Matt Long

Published: 2014-11-05T19:43:51Z

Content type: tutorial

Language: en

Sources: [Cocoa Is My Girlfriend](<https://devfeed.tech/sources/cocoa-is-my-girlfriend.md>)

Topics: [Swift](<https://devfeed.tech/topics/swift.md>), [Objective-C](<https://devfeed.tech/topics/objective-c.md>), [coding](<https://devfeed.tech/topics/coding.md>)

Tags: [coding](<https://devfeed.tech/tags/coding.md>), [crash](<https://devfeed.tech/tags/crash.md>), [objective-c](<https://devfeed.tech/tags/objective-c.md>), [playground](<https://devfeed.tech/tags/playground.md>), [playgrounds](<https://devfeed.tech/tags/playgrounds.md>), [swift](<https://devfeed.tech/tags/swift.md>)

### AI overview

This tutorial explains how Swift's map can replace Objective-C's valueForKeyPath: for extracting properties from collections, including nested properties. It also compares Swift optional unwrapping with the more crash-resistant behavior of Foundation APIs when data is unpredictable.

### Source excerpt

tl;dr; Download the Value For Key Path Playground I was incredibly disappointed in Swift when I started to look into how key value coding might be preserved in the transition from Objective-C. Of course, Apple would preserve that, right? And I don't mean by resorting to using Foundation classes-you know all type-casty and everything (yeah, [...]