In Swift 3, everything is bridgeable to AnyObject due to the introduction of _SwiftValue (see this Q&A for more info), that can wrap anything that isn't directly bridgeable to Objective-C in an opaque Objective-C compatible box.
Therefore is AnyObject will always be true, as anything can be represented as an AnyObject via wrapping in a _SwiftValue.
One way to check whether a value is a reference type (as shown in this Q&A) is to type-check the type of the value against the metatype of AnyObject, AnyClass (aka AnyObject.Type).
For generics, if you want to check whether the static type of T is a reference type, you can do:
isObject = T.self is AnyClass
If you want to check whether the dynamic type of a value typed as T is a reference type (such as val in your example), you can use the type(of:) function on the unwrapped value, as the aforementioned Q&A suggests:
if let val = val {
isObject = type(of: val) is AnyClass
// ...
}
The difference between these two approaches is that when T is of type Any (or a non AnyObject abstract type), T.self is AnyClass will return false (which could be useful if you want a box where the value could be a reference or value type) – type(of: val) is AnyClass however, will return whether val itself is a reference type.
