Swift3 - how to call class or struct functions by name - swift3

Question

As I come from a JS background this is how I'd call a function by name stored in a variable:
var obj = {
foobar: function(param) {
// do something
}
};
var key = "foobar";
obj[key](123);
Now I would like to recreate this in Swift, for example:
struct obj = {
func foobar(param) {
// do something
}
}
let key:String = "foobar"
obj[key](123)
The above code unfortunately gives Type 'obj.Type' has no subscript members
Is there any way to call functions by names in a Struct, Class or a Dictionary (if it's even possible to store functions in Dicts?)
EDIT - MORE CONTEXT:
I have a user-supplied array of things say:
let arr = ["apples", "oranges", "pears"]
but this array can be as long as 20 items. Based on each item of the array I need to perform certain action. So I iterate over the array:
for (key, _) in arr {
if (key == "apples") {
handleApples()
}
if (key == "oranges") {
handleOranges()
}
// and so on...
}
Sure, I can have a function with a simple switch that would consist of 20 cases but that's far from ideal. What if my array grows to say 100 items?
I was hoping to achieve something similar to this:
for (key, _) in arr {
myClass[key]()
}

Answer 1

Is there any way to call functions by names in a Struct, Class or a Dictionary (if it's even possible to store functions in Dicts?)
Yes you can store a function into a dictionary
Let's define a function type
typealias FuncType = () -> ()
and 2 functions
func func0() {
print("Apples")
}
func func1() {
print("Oranges")
}
Now we can create a dictionary where the key is String and the value is FuncType
let dict : [String:FuncType] = [
"Apples" : func0,
"Oranges" : func1
]
And of course we can invoke a function stored into the dictionary
dict["Apples"]?() // prints "Apples"

Answer 2

I think this might be what you're looking for:
var obj: [String: Int] = {
// do something, like call foobar(param) that's defined outside of the variable
// or just manipulate data directly in here
return ["foobar": 123]
// or whatever dictionary you want that matches the type you defined for obj
}()
Kind of tough to give you a better answer without you posting the kind of output or behavior you're looking for.