JSONPath for Swift.
Both dialects. No dependencies.

import JSONPath

let document = try JSONValue(parsing: """
    {"store": {"book": [
      {"category": "reference", "author": "Nigel Rees", "title": "Sayings of the Century", "price": 8.95},
      {"category": "fiction", "author": "Herman Melville", "title": "Moby Dick", "isbn": "0-553-21311-3", "price": 8.99},
      {"category": "fiction", "author": "J. R. R. Tolkien", "title": "The Lord of the Rings", "price": 22.99}
    ], "bicycle": {"color": "red", "price": 19.95}}}
    """)

let cheap = try JSONPath("$.store.book[?@.price < 10].title")
try cheap.values(in: document)         // ["Sayings of the Century", "Moby Dick"]
try cheap.paths(in: document)          // [$['store']['book'][0]['title'], $['store']['book'][1]['title']]
try cheap.nodes(in: document)          // locations + values
try document.query("$..price")         // [8.95, 8.99, 22.99, 19.95]

try JSONPath("$.store.book[?match(@.author, '.*Tolkien')].title").values(in: document)
try JSONPath("$.store.book[?count(@.isbn) > 0].title").values(in: document)

let fiction = try JSONPath("store.book[?(@.category == 'fiction' && @.price > 10)].title", dialect: .jayway)
let pattern = try JSONPath("$..book[?(@.author =~ /.*REES/i)].price", dialect: .jayway)
let count   = try JSONPath("$.store.book.length()", dialect: .jayway)          // [3]
let inList  = try JSONPath("$.store.book[?(@.category in ['fiction'])]", dialect: .jayway)

try JSONPath(anyDialect: "$.store.book[?@.price < 10]").dialect    // .rfc9535
try JSONPath(anyDialect: "$.store.book.length()").dialect          // .jayway

let title = try JSONPointer("/store/book/0/title")
title.resolve(in: document)                     // "Sayings of the Century"
title.tokens                                    // ["store", "book", "0", "title"]
try JSONPointer("#/store/bicycle")              // the URI fragment form is accepted
try JSONPointer("/a~1b/m~0n").tokens            // ["a/b", "m~n"]: `~1` is "/", `~0` is "~"
JSONPointer(tokens: ["a/b", "m~n"]).description // "/a~1b/m~0n"
try JSONPointer("/store/missing").resolve(in: document)  // nil

// From a query's results to pointers
try JSONPath("$..price").paths(in: document).map(\.jsonPointer.description)
// ["/store/book/0/price", "/store/book/1/price", "/store/book/2/price", "/store/bicycle/price"]

// Setting a value: missing object members are created, and `-` appends to an array
var copy = document
try copy.set("red", at: JSONPointer("/store/bicycle/color"))
try copy.set(["title": "Dune", "price": 9.99], at: JSONPointer("/store/book/-"))

var copy = document
try copy.replace(JSONPath("$..price"), with: 0)
try copy.remove(JSONPath("$.store.bicycle"))
try copy.map(JSONPath("$..title")) { .string($0.stringValue!.uppercased()) }   // return nil to remove
try copy.set("new", at: JSONPointer("/store/book/0/tag"))
try copy.set(1, at: NormalizedPath(["store", "book", 0, "price"]))

struct Book: Codable { let title: String; let price: Double }
let books = try JSONValueDecoder().decode(Book.self, from: JSONPath("$.store.book[*]").values(in: document))
let value = try JSONValue(encoding: books)        // keeps key order
print(value.jsonString(prettyPrinted: true))

JSONPath.validate("$.store[?@.price <]")       // a description of the error, or nil when valid

do {
    _ = try JSONPath("$.a[", dialect: .rfc9535)
} catch let error as JSONPath.ParseError {
    print(error.message, error.position)
}

let query = "$[?@.price < 10].title"
for token in JSONPath.tokens(in: query) {
    print(token.kind, query[token.range])    // root $, bracket [, punctuation ?, current @, …
}