Global Popover Function in Swift 1.2 on iOS 8 - ios

Question

I have this function that I use all over my app, and it would be nice to create a global function:
class CustomReportVC: UIViewController, UIAdaptivePresentationControllerDelegate, UIPopoverPresentationControllerDelegate {
func showPicker(pickerValues:[String], field:UITextField) -> AnyPickerVC{
//Set up modal
let storyboard = UIStoryboard(name: "Popovers", bundle: nil)
let modal = storyboard.instantiateViewControllerWithIdentifier("AnyPickerModal") as! AnyPickerVC
modal.modalPresentationStyle = UIModalPresentationStyle.Popover
let pc = modal.popoverPresentationController
pc?.permittedArrowDirections = .Down
pc?.sourceView = field
pc?.sourceRect = field.bounds
modal.preferredContentSize = CGSizeMake(300,180)
pc?.delegate = self
//Pass in data
modal.data = pickerValues
//Set the value from within the picker controller
modal.passDataToParent = { (value) in
field.text = value
}
return modal
}
//Required for the popover
func adaptivePresentationStyleForPresentationController(controller: UIPresentationController) -> UIModalPresentationStyle {
return .None
}
}
The issue I'm running into comes with pc?.delegate = self. Since CustomReportVC conforms to UIPopoverPresentationControllerDelegate, this works fine.
But once I attempt to create this as a global function outside a class that conforms to this protocol, I get an error:
func globalShowPicker(pickerValues:[String], field:UITextField, controller:UIViewController) -> AnyPickerVC{
//...
pc?.delegate = controller //<-- ( ! ) Type UIViewController does not conform to UIPopoverPresentationControllerDelegate
}
Whether I make controller a UIViewController or AnyObject, it doesn't conform. Is there a way to pass in the protocol conformity to the global function somehow?
Any idea how I can pull this off? Thanks. :)

Answer 1

Make your global function generic to specify that it only works for certain kinds of UIViewControllers. In this example, T can take the value of any UIViewController type which also conforms to the other protocols listed.
func globalShowPicker< T: UIViewController where
T: UIPopoverPresentationControllerDelegate,
T: UIAdaptivePresentationControllerDelegate >
(pickerValues:[String], field:UITextField, controller: T) -> AnyPickerVC
{
//...
pc?.delegate = controller
return blah
}
It does get kinda long, and I haven't figured out the best way to indent all the constraints. But it works.

Answer 2

Try adding a making a new class that inherits from both of them. Like this.
class PopoverController: UIViewController, UIPopoverPresentationControllerDelegate {
}
Then, switch the function to look like this.
func globalShowPicker(pickerValues:[String], field:UITextField, controller: PopoverController) -> AnyPickerVC{
//...
pc?.delegate = controller
}

Answer 3

You can pass the delegate as a parameter in the function like this:
class CustomReportVC: UIViewController, UIAdaptivePresentationControllerDelegate, UIPopoverPresentationControllerDelegate {
class func showPicker(pickerValues:[String], field:UITextField, delegate: UIPopoverPresentationControllerDelegate) -> UIViewController {
//Set up modal
let storyboard = UIStoryboard(name: "Popovers", bundle: nil)
let modal = storyboard.instantiateViewControllerWithIdentifier("AnyPickerModal") as! UIViewController
modal.modalPresentationStyle = UIModalPresentationStyle.Popover
let pc = modal.popoverPresentationController
pc?.permittedArrowDirections = .Down
pc?.sourceView = field
pc?.sourceRect = field.bounds
modal.preferredContentSize = CGSizeMake(300,180)
pc?.delegate = delegate
//Pass in data
modal.data = pickerValues
//Set the value from within the picker controller
modal.passDataToParent = { (value) in
field.text = value
}
return modal
}
//Required for the popover
func adaptivePresentationStyleForPresentationController(controller: UIPresentationController) -> UIModalPresentationStyle {
return .None
}
}
You have at the end to have an instance of a view controller that does conform to the protocol, but that way you will have the function global just like you want and pass self pointer in the view controller that does conform to the protocol "UIPopoverPresentationControllerDelegate":
CustomReportVC.showPicker(pickerValues:....., delegate: self)

Answer 4

Something like this?
self.presentViewController(pc, animated: true, completion: nil)
Btw, if you're doing Universal you can not present iPad UIActivityViewController like iPhone. You need to present it in a popover as per the design guidelines suggested by Apple.
or as an example
#IBAction func shareButtonClicked(sender: UIButton)
{
let textToShare = "Text"
if let myWebsite = NSURL(string: "http://www.example.com/")
{
let objectsToShare = [textToShare, myWebsite]
let activityVC = UIActivityViewController(activityItems: objectsToShare, applicationActivities: nil)
var nav = UINavigationController(rootViewController: activityVC)
nav.modalPresentationStyle = UIModalPresentationStyle.Popover
var popover = nav.popoverPresentationController as UIPopoverPresentationController!
activityVC.preferredContentSize = CGSizeMake(500,600)
popover.sourceView = self.view
popover.sourceRect = CGRectMake(100,100,0,0)
self.presentViewController(nav, animated: true, completion: nil)
}
}
class MyViewController : UIViewController, UIPopoverPresentationControllerDelegate {
//code here
}