All of the subclasses has a static function `update` and I have to call them for each subclass:

```
class subClass1 {
    static func update() { ... }
}

subClass1.update()
subClass2.update()
subClass3.update()

```

I hope I can construct an array to store them and call them like this:

```
let allSubClasses: [baseClass.Type] = [
    subClass1.self,
    subClass2.self,
    subClass3.self,
]

for var i=0; i<allSubClasses.count; ++i {
    allSubClasses[i].update()  // something like this, how to achieve it?
}

```

How to do it correctly?