A function for showing alerts and action sheets, written for iOS 7 and 8

showAlert.swift

import UIKit

// Notes:
// - You must explicitly weak link to UIKit to support iOS 7
// - Action sheets on iOS 7 only show a title

func showAlert(viewController: UIViewController, style: UIAlertControllerStyle = .Alert, title: String? = nil, message: String? = nil, sourceView: UIView? = nil, completion: (() -> ())? = nil, buttons: (UIAlertActionStyle, String, (() -> ())?)...) {
    
    if (NSClassFromString("UIAlertController") != nil) {
        // iOS 8+
        let alertController = UIAlertController(title: title, message: message, preferredStyle: style)
        for button in buttons {
            alertController.addAction(UIAlertAction(title: button.1, style: button.0) { (_: UIAlertAction!) in
                if let completion = completion { completion() }
                if let cb = button.2 { cb() }
            })
        }
        if let sourceView = sourceView {
            if let popoverPresentationController = alertController.popoverPresentationController {
                popoverPresentationController.sourceView = sourceView
                popoverPresentationController.sourceRect = sourceView.bounds
            }
        }
        
        viewController.presentViewController(alertController, animated: true, completion: nil)
        
    } else {
        // iOS 7
        class Helper: NSObject {
            
            var holdSelf: Helper?
            var cb: (Int) -> ()
            
            init(cb: (Int) -> ()) {
                self.cb = cb
                super.init()
                self.holdSelf = self
            }
            
            func finish(index: Int) {
                self.cb(index)
                self.holdSelf = nil
            }
        }

        switch style {
        case .ActionSheet:
            class ActionSheetHelper : Helper, UIActionSheetDelegate {
                init(_ actionSheet: UIActionSheet, cb: (Int) -> ()) {
                    super.init(cb: cb)
                    actionSheet.delegate = self
                    
                }
                func actionSheet(actionSheet: UIActionSheet!, clickedButtonAtIndex buttonIndex: Int) {
                    actionSheet.delegate = nil
                    self.finish(buttonIndex)
                }
            }
            let actionSheet = UIActionSheet()
            if let title = title {
                actionSheet.title = title
            }
            for button in buttons {
                actionSheet.addButtonWithTitle(button.1)
                switch button.0 {
                case .Default:
                    break
                case .Cancel:
                    actionSheet.cancelButtonIndex = actionSheet.numberOfButtons - 1
                case .Destructive:
                    actionSheet.destructiveButtonIndex = actionSheet.numberOfButtons - 1
                }
            }
            ActionSheetHelper(actionSheet) {
                if let completion = completion { completion() }
                if let cb = buttons[$0].2 { cb() }
            }
            if let sourceView = sourceView {
                actionSheet.showFromRect(sourceView.bounds, inView: sourceView, animated: true)
            } else {
                actionSheet.showInView(viewController.view)
            }
        case .Alert:
            class AlertHelper : Helper, UIAlertViewDelegate {
                init(_ alertView: UIAlertView, cb: (Int) -> ()) {
                    super.init(cb: cb)
                    alertView.delegate = self
                    
                }
                func alertView(alertView: UIAlertView!, clickedButtonAtIndex buttonIndex: Int) {
                    alertView.delegate = nil
                    self.finish(buttonIndex)
                }
            }
            let alertView = UIAlertView()
            if let title = title {
                alertView.title = title
            }
            if let message = message {
                alertView.message = message
            }
            for button in buttons {
                alertView.addButtonWithTitle(button.1)
                switch button.0 {
                case .Cancel:
                    alertView.cancelButtonIndex = alertView.numberOfButtons - 1
                default:
                    break
                }
            }
            AlertHelper(alertView) {
                if let completion = completion { completion() }
                if let cb = buttons[$0].2 { cb() }
            }
            alertView.show()
        }
        
    }
}

Hey, it looks like the UIAlertViewDelegate clickedButtonAtIndex method signature changed since you wrote this code which causes the delegate method to never be called on iOS7. If you change the alertView parameter from UIAlertView! to UIAlertView it works again :)

@ifabijanovic were you able to get this to work? I'm still having the problem of the delegate method never getting called on iOS7. Any ideas? I made the change you suggested but still nothing. I'm running XCode 6.3.1 and Swift 1.2 on an iPhone 4S running 7.0.1.

How to use this?

how yo use this?