If you have a background in languages with extensive reflection support you will notice that there is a lot missing from Swift. Reflection API in the new Swift 2 is rather basic allowing you to access a tiny amount of information.
Note: I used XCode Version 7.0 beta 5, you will need at least XCode 7 to run the below code.
Here is an example class and struct that later I will introspect using Reflection API.
I created one class representing person and one struct for address information. These might not be the best ways to store that information but it gives me an oportunity to show you how they interact with reflection API.
Let’s have a look at the reflection code.
The above code extracts pretty much all the information you can access through the reflection API. Let me explain what is happening.
Mirror is a structure that desribes the internals of a particular instance e.g. properties. You create a Mirror by passing in the object you want to know more about.
It provides information about a static type of the reflected instance.
Used mainly by Playgrounds and debugger. It describes how the instance should be displayed.
Textual description of the mirror
Collection of Child objects. Each one describing one property of the instance. Child is defined as follows:
label provides information about the property name and value gives you it’s value. You can use dynamicType property on the value to access its Type.
Now that we know what the above code does, here is how to invoke it with a example Person object:
Below is the output that was produced when inspect was called with person and person.address respectively:
As you can see, the reflection API is rather basic in comparison to other languages. In all fairness, Swift is a young language which is still under heavy development. In the future we will definately see more developments in this area.