Value type is AnyObject! Why?

[hamishknight]

This is correct (albeit unintuitive at first) behaviour, and is a result of id-as-Any. See the following thread for more info:

Any as AnyObject

I spotted a bug in a 3rd party library where a parameter type should be [String: Any]? instead of [String: AnyObject]?. While converting that dictionary I noticed that doing anyInstance as? AnyObject will raise a warning "Conditional cast from 'Any' to 'AnyObject' always succeeds". That behavior was unexpected since not every type is a reference type, hence not every any instance should be implicitly an any object instance. I know there are implicit wrapper types behind the scenes for Objective…

Regarding your example with the array:

let array: [AnyObject] = []

if array is [Int] {
    print("// yes [AnyObject] is [Int]")
}

it's worth noting that currently empty arrays can be cast to any array type. For example:

let array: [String] = []

if array is [Int] {
  print("yup")
}
// prints: yup

There's some discussion of this behaviour in the comments of SR-6192.