协议作为快速冲突中的参数类型

Question

I am using external SDK(by including their xcode project in my project). The SDk was working properly in objective-c, but when I switched to swift, I am getting following problem.

Whenever I implementing delegate method where parameter is of type protocol, xcode suddenly gives error to object declaration of that Class which declared globally ie not in any function. If I comment that particular delegate method I will not get any error and it compile/executes successfully.

Please check the following swift code followed by my # comments

//CustomView is subclass of UIView
        var customview : CustomView = CustomView() // #1 error as : Use of undeclared type CustomView
        @IBAction func showCustomView(sender: AnyObject) 
        {    
        // CustomView configurations 
        }

    #pragma CustomView Delegates
        func CustomViewShown(view: AnyObject!) /// #2 delegate work properly
        {

        }

        func CustomView(view: AnyObject!, didFailWithError error: NSError!) 
    // #3 if I keep this method uncommented it gives error to #1 line  
    // if I commented this method all other works fine without error.
        {

        }

Surprising thing is all the above delegate and SDK works fine for objective-C but not for swift.

On the basis of my little research, I am concluding that, We can not use the Class name and method name same in swift, ie in my case its CustomView. If I am using CustomView for declaring object, I can not use it as method name.

so someone please verify that, I am correct or not ? and what is solution for this issue.

Answer 1

It's essentially a name conflicting problem.

Inside of your class declaration, CustomView is a method name, but not a class name. So, basically, your assumption is correct.

But, you have a workaround.

Let's suppose CustomView is declared in the SDK. And that is a framework named SomeSDK . Then you can reference the CustomView like this:

import SomeSDK

class ViewController: UIViewController {

    var customview: SomeSDK.CustomView = SomeSDK.CustomView()

    func CustomView(view: AnyObject!, didFailWithError error: NSError!) {
    }
}

If you don't want to prefix SomeSDK. everywhere, you can typealias it:

import SomeSDK

typealias SDKCustomView = CustomView // you can use `CustomView` here because there is no conflicting name.

class ViewController: UIViewController {

    var customview: SDKCustomView = SDKCustomView()

    func CustomView(view: AnyObject!, didFailWithError error: NSError!) {
    }
}

Answer 2

I may be wrong, but it seems in swift you can also explicitly call the init function.

Instead of calling:

var customview : CustomView = CustomView()

you can call:

var customview : CustomView = CustomView.init()

This works in my Playground, let me know how it works out for you. This would allow you to use your function named as it is.