Swift class introspection & generics
introspection, swift
Solution
Well, for one, the Swift equivalent of `[NSString class]` is `.self` (see Metatype docs, though they're pretty thin).
In fact, `NSString.class` doesn't even work! You have to use `NSString.self`.
let s = NSString.self
var str = s()
str = "asdf"
Similarly, with a swift class I tried...
class MyClass {
}
let MyClassRef = MyClass.self
// ERROR :(
let my_obj = MyClassRef()
Hmm… the error says:
Playground execution failed: error: :16:1: error: constructing an object of class type 'X' with a metatype value requires an '@required' initializer
Y().me()
^
<REPL>:3:7: note: selected implicit initializer with type '()'
class X {
^
It took me a while to figure out what this means… turns out it wants the class to have a `@required init()`
class X {
func me() {
println("asdf")
}
required init () {
}
}
let Y = X.self
// prints "asdf"
Y().me()
Some of the docs refer to this as `.Type`, but `MyClass.Type` gives me an error in the playground.
Problem
I am trying to dynamically create a `class` instance based type using generics, however I am encountering difficulty with class introspection. Here are the questions: - Is there a Swift-equivalent to Obj-C's `self.class`? - Is there a way to instantiate a class using the `AnyClass` result from `NSClassFromString`? - Is there a way to get `AnyClass` or otherwise type information strictly from a generic parameter `T`? (Similar to C#'s `typeof(T)` syntax)