How do I find all the property keys of a KVC compliant Objective-C object?

Question

Is there a method that returns all the keys for an object conforming to the NSKeyValueCoding protocol?

Something along the lines of [object getPropertyKeys]

Answer 1

For Swift onlookers, you can get this functionality by utilising the Encodable functionality. I will explain how:

1. Conform your object to Encodable protocol

   class ExampleObj: NSObject, Encodable {
       var prop1: String = ""
       var prop2: String = ""
   }
   

2. Create extension for Encodable to provide toDictionary functionality

    public func toDictionary() -> [String: AnyObject]? {
       let encoder = JSONEncoder()
       encoder.outputFormatting = .prettyPrinted
       guard let data =  try? encoder.encode(self),
             let json = try? JSONSerialization.jsonObject(with: data, options: .init(rawValue: 0)), let jsonDict = json as? [String: AnyObject] else {
           return nil
       }
       return jsonDict
   }
   

3. Call toDictionary on your object instance and access keys property.

   let exampleObj = ExampleObj()
   exampleObj.toDictionary()?.keys
   

4. Voila! Access your properties like so:

   for k in exampleObj!.keys {
       print(k)
   }
   // Prints "prop1"
   // Prints "prop2"