Reflex

Reflex is an extension module for FLEX that brings first-class Swift type inspection to the debugger. Without Reflex, FLEX relies solely on the Objective-C runtime, which means that pure Swift classes, structs, enums, and their stored properties are either invisible or misrepresented in the inspector.

Reflex closes this gap by bridging Echo — a library that reads Swift's own runtime type metadata directly — into the FLEXMirrorProtocol interface that FLEX uses to inspect any object. The result is that Swift types appear in FLEX with correctly-named ivars, proper type encodings, accurate sizes and offsets, and full protocol-conformance lists, just as if they were plain Objective-C objects.

Note: Because Reflex depends on FLEX, which uses private Apple APIs, it cannot be included in an App Store submission. It is intended exclusively for use in debug builds.

Features

• Surfaces stored properties on pure Swift classes that the ObjC runtime cannot see.
• Correctly reports field names, types, sizes, and byte offsets for every Swift ivar.
• Supports getting and setting Swift ivar values through FLEX's inspector UI.
• Handles optional types correctly — setting nil uses _openExistential to produce a properly-typed Optional.none rather than naively zeroing memory.
• Bridges Foundation value types (String, Data, URL, Date, [T], [K:V]) to their Objective-C class equivalents for correct type encoding.
• Exposes Swift protocol conformances alongside ObjC protocols in the protocols list.
• Traverses the full class hierarchy when getting or setting values, including fields declared on superclasses.
• Provides accurate type encoding strings for scalars, structs, tuples, enums, and bridged types.
• Gracefully handles non-Swift types, ObjC classes, and __SwiftValue boxes without crashing.
• Fully interoperable with Objective-C via FLEXSwiftMirror, FLEXSwiftIvar, and FLEXSwiftProtocol.

Usage

Reflex is designed to integrate directly with FLEX. Register SwiftMirror as FLEX's Swift mirror class at launch and the debugger will automatically use it when reflecting Swift objects.

import FLEX
import Reflex

// In your AppDelegate or debug setup code:
FLEXManager.shared.swiftMirrorClass = SwiftMirror.self

You can also use SwiftMirror independently to inspect any Swift object at runtime:

import Reflex

let inspector = SwiftMirror(reflecting: someSwiftObject)

// Print all ivar names, types, and current values
for ivar in inspector.ivars {
    let value = ivar.getValue(someSwiftObject) ?? "nil"
    print("\(ivar.name): \(ivar.typeEncoding) = \(value)")
}

// Traverse the class hierarchy
var mirror: FLEXMirrorProtocol? = inspector
while let current = mirror {
    print("Class: \(current.className), ivars: \(current.ivars.count)")
    mirror = current.superMirror
}

Setting values works too — Reflex handles type mismatches such as NSNumber being passed for an Int field by performing a dynamic cast first:

// Directly set a field value by name on a Swift class instance
let meta = reflectClass(someObject) as! ClassMetadata
meta.set(value: "New Value", forKey: "title", pointer: someObject~)

Requirements

• iOS 12.0 or later
• Swift 5.0 or later
• FLEX 4.6 or later
• Echo

Installation

Swift Package Manager

Add the following to your Package.swift dependencies:

.package(url: "https://github.com/TimOliver/Reflex", from: "1.0.0")

Then add "Reflex" to your target's dependencies array.

Credits

Reflex was created by Tanner Bennett, and builds upon Echo by Alejandro Alonso.

License

Reflex is available under the BSD license. Please see the LICENSE file for more information. Note that because this library depends on FLEX, which uses private Apple APIs, it cannot be used in App Store submissions.