Скачать или смотреть Understanding Xcode Protocol Stubs: Why Isn't My Struct Yelling?

Learn why Xcode doesn't require protocol stubs for your `Hashable` structs and how to customize their functionality if needed.
---
This video is based on the question https://stackoverflow.com/q/62967562/ asked by the user 'Max' ( https://stackoverflow.com/u/11852570/ ) and on the answer https://stackoverflow.com/a/62967589/ provided by the user 'Frankenstein' ( https://stackoverflow.com/u/7098650/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Xcode does not offers to add protocol stubs

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding Xcode Protocol Stubs: Why Isn't My Struct Yelling?

When working with Swift in Xcode, you might have encountered a situation where your custom types are expected to conform to certain protocols. For instance, suppose you have created a struct intended to implement the Hashable protocol for use in a dictionary, yet Xcode doesn't prompt you to add any protocol stubs. This can be perplexing if you're expecting an error just like how Xcode typically indicates absence of protocol conformance. Let's delve into why this happens and how you can manage protocol conformance more explicitly in your Swift structs.

The Problem: Missing Protocol Compliance Errors

You might find yourself in a situation where you define a struct like this:

[[See Video to Reveal this Text or Code Snippet]]

In this code, you're attempting to make the Card struct conform to Hashable. However, Xcode does not display any errors nor does it prompt you to add any protocol stubs, leaving you confused about the next steps. So, what's going on here?

The Solution: Automatic Protocol Conformance

The reason Xcode is quiet about protocol stubs is that Swift automatically synthesizes the Hashable conformance for your struct. When your struct includes properties that themselves conform to Equatable and Hashable, Swift can automatically generate the necessary implementations for you.

Implications of Automatic Synthesis

You don't need to manually implement the hash(into:) function unless you want to customize the hashing behavior.

The synthesized implementation uses all stored properties that conform to Hashable to generate the hash value.

Customizing Protocol Conformance

If you need to customize how your struct conforms to Hashable, you can override the default behavior by implementing the hash(into:) method. This is useful if you want to change which properties are used for generating hash values or to modify the way hashing is done. Here's how you can do it:

[[See Video to Reveal this Text or Code Snippet]]

Benefits of Customization:

Control over the hash generation process.

Potential improvements in performance for specific use cases.

Better handling of struct values that need unique hashing.

Conclusion

In conclusion, the lack of protocol stub prompts when using Xcode with Swift structs that conform to Hashable is due to Swift's powerful protocol synthesis capabilities. You can use this feature to your advantage and only override the default implementations if you require specific behavior. This streamlines your coding process and allows you to focus on more critical implementation details.

If you have any comments or further questions about working with protocols in Swift and Xcode, feel free to share your thoughts!