How are global functions defined in Swift?

function, global, swift

Solution

Unless you declare the function as `private` or `fileprivate`, which limit the visibility to the file or scope where it is defined, you can use it anywhere in the module if declared as `internal` (the default), and also from external modules if declared as `public` or `open`.

However since you say that you need it in view controllers only, why not implementing it as an extension to the view controller?

extension UIViewController {
    func displayAlert(title:String, error:String, buttonText: String) {
        ...
    }
}

Problem

I wrote a simple function that displays an alert when it is called. I'd like to use this function in several viewControllers. Right now I have the same bit of code copy-pasted into the bottom of each viewController, but I can't help but think there's a better way. How can one define a function that can be called from any viewController? Just for reference I'll paste my function below, but this is a general question. I'd like to be able to find an eloquent way to handle keyboard management identically across all view controllers as well. ``` func displayAlert(title:String, error:String, buttonText: String) { // Create the alert var alert = UIAlertController(title: title, message: error, preferredStyle: UIAlertControllerStyle.Alert) // Add an action alert.addAction(UIAlertAction(title: buttonText, style: .Default, handler: { action in // Dismiss when the button is pressed self.dismissViewControllerAnimated(true, completion: nil) })) // Add it to viewController self.presentViewController(alert, animated: true, completion: nil) } ```

Original source