SwiftUI: Why UIHostingController(rootView:) can pass nil value? - swiftui

Question

In Xcode playground :
func makeView<T:View>(v: T) -> T?{
nil
}
let v0 = makeView(v: Text(""))
let view = UIHostingController(rootView: v0)
note that func UIHostingController(rootView: ) signature not allowed pass nil value:
open class UIHostingController<Content> : UIViewController where Content : View {
public init(rootView: Content)
}
So why I can pass nil to UIHostingController(rootView:) ???
thanks ;)
Update:
So I try to write some one like class UIHostingController：
protocol P{
var name: String {get}
}
class Container<T> where T: P{
init(a:T){
print(a.name)
}
}
struct A: P {
var name:String
init?(name:String) {
if name.isEmpty{
return nil
}
self.name = name
}
}
but when I create a instance of Container, some wrong happens:
let p = Container(a: A(name: ""))
compiler complain me ：
Argument type 'A?' does not conform to expected type 'P'
So how UIHostingController did that???

Answer 1

In the below code, it's true that V0 is nil. But, it's important to note that v0 is of type Text?.
let view = UIHostingController(rootView: v0)
Even though below line doesn't work
let view = UIHostingController(rootView: nil)
This works.
let view = UIHostingController<Text?>(rootView: nil)
To fix the error "Generic class 'Container' requires that 'A?' conform to 'P'", Container class can be updated as below
class Container<T>: X where T: P{
init(a:T?){
if let a = a {
print(a.name)
}
}
}