Swift - 将自定义对象作为参数传递

Question

I started learning Swift today and in my first test app I am getting this error:

TestClass is not convertible to AnotherClass

The following is the TestClass :

class TestClass : NSObject {

    var parameter1 : String = ""
    var parameter2 : String = ""

    override init() {        
        super.init()
    }

    func createJob(parameter1: String, parameter2: String) -> TestClass {
        self.parameter1 = parameter1
        self.parameter2 = parameter2
        return self;
    }  
}

And this is the AnotherClass :

class AnotherClass: NSObject {

    private struct internalConstants {
        static let test1 = "testData"
        static let test2 = "testData2"
    }

    var current : String

    override init() {
        self.current = internalConstants.test1
        super.init()
    }

    func executeTask(testClass : TestClass) {

        if testClass.parameter1 == "abc" {
            return;
        }
    }
}

And this is the ViewController where I am getting the compiler error:

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let obj = TestClass()
        AnotherClass.executeTask(obj)
    }

}

AnotherClass.executeTask line is giving the compiler error.

The obj variable sent as a parameter on this line is highlighted by Xcode with the error

" TestClass is not convertible to AnotherClass ".

In C# or Objective C it is allowed to pass custom objects as a parameter to another methods. How can I do it in Swift?

Answer 1

Let's correct first the TestClass . This is how you should init a class like that:

class TestClass : NSObject {

    ....

    init(parameter1: String, parameter2: String) {
        ....
    }
}

Much simpler. Now, going back to your problem,

"TestClass is not convertible to AnotherClass".

Take a look at it again. The line you've mentioned in your question. You are trying to do this:

let obj = TestClass()
AnotherClass.executeTask(obj)

This line, AnotherClass.executeTask(obj) , is giving you an error because indeed executeTask() is an instance method. You could do three ways for that.

1. add static keyword to the func executeTask... So it becomes like this: static func executeTask(testClass : TestClass) {

2. Instead of static keyword, you could add class . It becomes like so: class func executeTask(....

3. OR, better if you just instantiate the AnotherClass . Make a new object of AnotherClass . How to instantiate? You tell me. But here:

let anotherClass = AnotherClass()

Answer 2

Either implement executeTask as a class function

class func executeTask(testClass : TestClass) {
    if testClass.parameter1 == "abc" {
        return;
    }
}

or instantiate AnotherClass in vieweDidLoad

let obj = TestClass()
let another = AnotherClass()
another.executeTask(testClass: obj)

Note the slightly different call to executeTask with the argument name.

And there is really no reason for you to subclass NSObject as I see it.

Answer 3

I think it's best to keep is simple. Create an instance of AnotherClass inside of ViewController .

class ViewController: UIViewController {

    // Create an instance of AnotherClass which lives with ViewController.
    var anotherClass = AnotherClass()

    override func viewDidLoad() {
        super.viewDidLoad()

        let obj = TestClass()

        // Use the instance of AnotherClass to call the method.
        anotherClass.executeTask(testClass: obj)
    }

}