How to check object belong to class or struct in swift

Question

I got stuck by the question in swift. Suppose I have one object, how to check whether it is from struct or class in swift.

Answer 1

This approach has been working for me in Swift 3:

class TestClass { }
struct TestStruct { }

var mystery:Any

mystery = TestClass()
// Is mystery instance a class type?
print(type(of:mystery) is AnyClass ? "YES" : "NO") // prints: "YES"

mystery = TestStruct()
// Is mystery instance a class type?
print(type(of:mystery) is AnyClass ? "YES" : "NO") // prints: "NO"

Note that this approach tells you only if an instance is a class type or not. The fact that it's not a class doesn't necessarily mean it's a struct (could be an enum, closure, tuple, etc.) But for most purposes and contexts this is enough to know if you are dealing with a reference type or a value type, which is usually what is needed.

Answer 2

In Swift 3.0, you can call Mirror(reflecting:x).displayStyle where x is your value of interest. The result will be class, struct, enum, dictionary, set... see the documentation https://developer.apple.com/reference/swift/mirror.displaystyle

Code sample:

struct SomeStruct {
     var name: String
     init(name: String) {
          self.name = name
     } 
} 
var astruct = SomeStruct(name:"myname") 
Mirror(reflecting:astruct).displayStyle == .struct // will be true
Mirror(reflecting:astruct).displayStyle == .class; // will be false

class MyClass {
      var name:String
      init(name: String) {
          self.name=name
      }  
} 
var aclass = MyClass(name:"fsdfd")   
Mirror(reflecting:aclass).displayStyle == .struct // will be false
Mirror(reflecting:aclass).displayStyle == .class // will be true

Of course, it would be best handled using a switch-case statement in practice.