李二狗 — @Meniny
Table of Content
To return instancetype in Swift, you can define a generic helper method which infers the type of self from the calling context:
public extension UIViewController {
// Call this
public class func instance(storyboard sbname: String, bundle: Bundle? = nil, identifier: String?) -> Self {
return helper_instance(storyboard: sbname, bundle: bundle, identifier: identifier)
}
// Helper
private class func helper_instance<T>(storyboard sbname: String, bundle: Bundle?, identifier: String?) -> T {
let storyboard = UIStoryboard.init(name: sbname, bundle: bundle)
guard let id = identifier else {
return storyboard.instantiateInitialViewController() as! T
}
return storyboard.instantiateViewController(withIdentifier: id) as! T
}
}
then:
let controller = MyController.instance(storyboard: "Main", identifier: "MyController")
compiles, and the type is inferred as MyController now.
