swift wrap function in another function - ios

Question

I have a class to check internet connection that i found here: Check for internet connection with Swift
In my methods i use it:
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
if Reachability.isConnectedToNetwork() == false {
let alert = UIAlertView(title: "No Internet Connection", message: "Make sure your device is connected to the internet.", delegate: nil, cancelButtonTitle: "OK")
alert.show()
return
}
}
but can i make a decorator or something to write something like:
#check_internet_connection
override func viewWillAppear(animated: Bool) {
}
or for example use it for all methods in class:
#check_internet_connection
class MyClass: UIViewController {
...
}

Answer 1

In Swift these are called Attributes. Currently (as of Swift 2.1), you cannot define your own.
Why not write a global function to handle this?
// In global scope
func check_internet_connection() -> Bool {
if Reachability.isConnectedToNetwork() == false {
let alert = UIAlertView(title: "No Internet Connection", message: "Make sure your device is connected to the internet.", delegate: nil, cancelButtonTitle: "OK")
alert.show()
return false
} else {
return true
}
}
…
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
if !check_internet_connection() { return }
}

Answer 2

Inheritance Approach
You can create ReachabilityAwareViewController as base class.
class ReachabilityAwareViewController: UIViewController{
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
if Reachability.isConnectedToNetwork() == false {
// your code goes here
}
}
}
and create subclass that inherit all behaviour from ReachabilityAwareViewController.
class myViewController: ReachabilityAwareViewController{
// ..
}
Composition Approach
This approach looks more like the decorator. Using protocol extension
protocol ReachabilityAware{
func checkReachibility()
}
extension ReachabilityAware where Self: UIViewController{
func checkReachibility(){
if Reachability.isConnectedToNetwork() == false {
let alertController = UIAlertController(title: "No Internet Connection", message: "Make sure your device is connected to the internet.", preferredStyle: .Alert)
let okAction = UIAlertAction(title: "OK", style: .Cancel){ action in }
alertController.addAction(okAction)
presentViewController(alertController, animated: true, completion: nil)
}
}
}
class myViewController: UIViewController, ReachabilityAware{
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
checkReachibility()
}
}