Cannot explicitly specialize a generic function

Question

I have issue with following code:

func generic1(name : String){
}

func generic2(name : String){
     generic1(name)
}
         


        

Answer 1

Swift 5

Typically there are many ways to define generic functions. But they are based on condition that T must be used as a parameter, or as a return type.

extension UIViewController {
    class func doSomething() -> T {
        return T()
    }

    class func doSomethingElse(value: T) {
        // Note: value is a instance of T
    }

    class func doLastThing(value: T.Type) {
        // Note: value is a MetaType of T
    }
}

After that, we must provide T when calling.

let result = UIViewController.doSomething() as UIImageView // Define `T` by casting, as UIImageView
let result: UILabel = UIViewController.doSomething() // Define `T` with property type, as UILabel
UIViewController.doSomethingElse(value: UIButton()) // Define `T` with parameter type, as UIButton
UIViewController.doLastThing(value: UITextView.self) // Define `T` with parameter type, as UITextView

Ref:

1. http://austinzheng.com/2015/01/02/swift-generics-pt-1/
2. https://dispatchswift.com/type-constraints-for-generics-in-swift-d6bf2f0dbbb2