如何从另一个 swift 文件中调用函数

我是SWIFT的新手，我已经为数据处理创建了单独的SWIFT文件.它包括以下函数.我想用另一个快速文件调用它，我该怎么做呢？

import Foundation
import CoreData

internal struct DataManager{
    static let shared = DataManager()
    let persistentContainer: NSPersistentContainer = {
        let container = NSPersistentContainer(name: "eduDemo")
        container.loadPersistentStores {(storeDescription,error) in
            if let error = error {
                fatalError("Loading of store failed \(error)")
            }
        }
        
        return container
    }()



@discardableResult func createUser(email:String,password:String) -> Userdetails? {
    let context = persistentContainer.viewContext
    
    let userdetails = NSEntityDescription.insertNewObject(forEntityName: "Userdetails", into: context) as! Userdetails
    
    userdetails.email=email
    userdetails.password = password
    
    do {
        try context.save()
        return userdetails
    } catch let createError{
        print("Failed to create: \(createError)")
    }
    
    return nil
    
}

}

我正在try 调用的函数在另一个快速文件中的函数上面

  @IBAction func registerPressed(_ sender: Any) {
        
        let Email: String =  email.text!
        let Pwd: String = password.text!
        
        DataManager.createUser(email:Email, password: Pwd)
        
     
    } 

但它给了我以下错误.我在这里做错了什么.

Instance member 'createUser' cannot be used on type 'DataManager'; did you mean to use a value of this type instead?个