Escape strings in raw JSON output - #1201

Tests/SwiftJSONTests/RawTests.swift:132

• JSONSerialization.jsonObject(with:) commonly returns [Any] (or NSArray bridged to that), so conditionally casting to [String] may fail even when the JSON is valid. Cast to [Any] and then downcast the element to String to keep this regression test stable across Foundation implementations.

            let array = try JSONSerialization.jsonObject(with: Data(arrayRaw.utf8)) as? [String]
            XCTAssertEqual(array?.first, value)

Source/SwiftyJSON/SwiftyJSON.swift:627

• In the castNilToNSNull dictionary serialization path, the key is escaped repeatedly (2–4 times) within the same closure. This is unnecessary work and makes the closure harder to read; compute the escaped key once and reuse it for the null/string/non-string branches.

				let body = try dict.keys.map { key throws -> String in
					guard let value = dict[key] else {
						return "\"\(escapeJSONString(key))\": null"
					}
					guard let unwrappedValue = value else {

Tests/SwiftJSONTests/RawTests.swift:119

• JSONSerialization.jsonObject(with:) typically returns [String: Any] (or an NSDictionary bridged to that), so conditionally casting to [String: String] can fail even when the JSON is valid. Cast to [String: Any] and then downcast the value to String for a more robust regression test across platforms.

This issue also appears on line 131 of the same file.

            let object = try JSONSerialization.jsonObject(with: Data(dictRaw.utf8)) as? [String: String]
            XCTAssertEqual(object?[key], value)