realm / realm/SwiftLint

Rule Request: Warn on use of some NS types in Swift code

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rule-request
Dominant language
Swift
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Description

New Issue Checklist
New rule request

Please describe the rule idea, format
this issue's title as Rule Request: [Rule Name] and describe:

  1. Why should this rule be added? Share links to existing discussion about what
    the community thinks about this.

This would prevent developers from using legacy NS types where swift versions of those types already exist. Apple outlines guidance on which types get bridged here:

https://developer.apple.com/documentation/swift/imported_c_and_objective-c_apis/working_with_foundation_types

  1. Provide several examples of what would and wouldn't trigger violations.

Bad

All of the below types have a Swift analogue and should not be used in Swift code

let foo1: NSDictionary = bar1
let foo2 = NSArray()
let foo3: NSString = bar3
let foo4 = NSSet()

Ok

These types do not have a Swift analogue, so they should be allowed.

let vc = NSViewController()
let orderedSet = NSOrderedSet()
  1. Should the rule be configurable, if so what parameters should be configurable?

Unsure

  1. Should the rule be opt-in or enabled by default? Why?
    See README.md for guidelines on when to mark a rule as opt-in.

I think this rule should be opt-in. There is a lot of potential for flagging types that should be completely valid in normal Swift code, and in codebases where very particular Swift-ObjC is required.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Read README.md's opt-in rules guidance and use the Apple Foundation types documentation linked in the issue to define the rule's scope. The finished rule should flag the listed legacy types such as NSDictionary, NSArray, NSString, and NSSet while allowing NSViewController and NSOrderedSet, with its opt-in status documented.

Written by the indexing model from the issue text.

Assessment

Tech stack
swift
Domain
tooling
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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