CODEWITHSUNDEEP
swift
ixx
ixx

Reputation: 32273

How to check type against type parameter?

I'm trying to implement a UIViewController extensions that gets the first child view controller with a certain type.

I tried:

func getChildViewController(#type:UIViewController.Type) -> UIViewController? {
    for vc:UIViewController in self.childViewControllers as [UIViewController] {
        if vc is type { //<-- 'type is not a type'
            return vc
        }
    }
    return nil
}

And:

func getChildViewController(#type:Type) -> UIViewController? { // "Type", doesn't exist
    for vc:UIViewController in self.childViewControllers as [UIViewController] {
        if vc is type {
            return vc
        }
    }
    return nil
}

And this (partially derived from How to pass a class type as a function parameter):

func getChildViewController<T>(#type:T.Type) -> UIViewController? {
    for vc:UIViewController in self.childViewControllers as [UIViewController] {
        if vc is type { //<-- 'type is not a type'
            return vc
        }
    }
    return nil
}

Nothing works! How can I do this? Thanks!

Upvotes: 0

Views: 179

Answers (1)

Airspeed Velocity
Airspeed Velocity

Reputation: 40965

In your last example, change 

if vc is type

to 

if vc is T

T is the type you’re looking for, whereas T.Type is a metatype giving information about the type T. All you’re really using T.Type for is to fix T to be the type that you want when you call getChildViewController.

Upvotes: 2

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