MoveDataBetweenViewControllers.md

Move data between view Controllers

In Swift, there are several ways to move data between view controllers. Here are a few options:

• Using a segue: A segue is a visual transition from one view controller to another. You can use a segue to pass data between the view controllers. Here's an example:

In your first view controller, create a variable to hold the data you want to pass:

var myData: String = "Hello World"

Then, create a segue from your first view controller to your second view controller in your storyboard. Give the segue an identifier (e.g. "mySegue").

In your first view controller, override the prepare(for:sender:) method and pass the data to the second view controller:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "mySegue" {
        if let destinationVC = segue.destination as? SecondViewController {
            destinationVC.receivedData = myData
        }
    }
}

In your second view controller, create a variable to receive the data:

var receivedData: String?

Now, when the segue is performed, the prepare(for:sender:) method is called and the data is passed to the second view controller.

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• Using a delegate: A delegate is an object that acts on behalf of another object. You can use a delegate to pass data between view controllers. Here's an example:

In your first view controller, create a protocol to define the delegate methods:

protocol MyDelegate {
    func sendData(data: String)
}

Create a variable to hold the delegate:

var delegate: MyDelegate?

When you want to pass the data, call the delegate method:

delegate?.sendData(data: "Hello World")

In your second view controller, conform to the delegate protocol:

class SecondViewController: UIViewController, MyDelegate {
    // ...
    
    func sendData(data: String) {
        // Do something with the data
    }
}

Set the second view controller as the delegate of the first view controller:

let secondVC = SecondViewController()
secondVC.delegate = self

Now, when the data is passed, the delegate method is called in the second view controller.

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• Using a singleton: A singleton is a class that has only one instance. You can use a singleton to store data that can be accessed from multiple view controllers. Here's an example:

Create a singleton class:

class DataManager {
    static let shared = DataManager()
    
    var myData: String = "Hello World"
}

In your first view controller, set the data:

DataManager.shared.myData = "Hello World"

In your second view controller, access the data:

let data = DataManager.shared.myData

Now, the data can be accessed from anywhere in your app.