alertControllers in swift - ios

Question

I am having a couple of issues with alert controllers in swift. I have two functions for displaying activity indicators. 1 with animation, and one without. The reason for creating the second one without an animation was because.. I am displaying an activity on a view controller when a user clicks on a table view cell and is segued to a new controller. This controller calls a webservice and populates a second table view.
My problem was that the web service was returning a response so quick that the activity indicator wasn't up on screen when I was trying to dismiss it i.e. in the repsonse of the webservice call. I was presenting this indicator in the viewdidload and then calling the web service function in the view did load after.
The only way i could get around this was to create an activity alert which did not have an animation as it seemed as though the animation was slowing it down a bit. But when I set the animation property to false, the alert controller did not have a backgroundColor. When I try to add a background color to the alert controller, the width changes to full screen.
So I'm looking for:
A) a way around dismissing the regular alert controller when the web service returns too quickly
or
B) to reduce the size of the second alert controller which has no animation.
Thanks in advance. I was having a lot of trouble with dismissing these alert controllers in that when I was attempting to dismiss them, my actual view controller was being dismissed so I tried to check the class of the presentedController and only dismissing if the class was alertController but I don't think this is actually the right way to go around it at all.
Code below:
func displayActivityAlert(title: String, #ViewController: UIViewController)
{
let pending = UIAlertController(title: "\n\n\n"+title, message: nil, preferredStyle: .Alert)
//create an activity indicator
let indicator = UIActivityIndicatorView(frame: pending.view.bounds)
indicator.autoresizingMask = .FlexibleWidth | .FlexibleHeight
indicator.color = UIColor(rgba: Palette.accent)
//add the activity indicator as a subview of the alert controller's view
pending.view.addSubview(indicator)
//pending.view.backgroundColor = UIColor.whiteColor()
indicator.userInteractionEnabled = false // required otherwise if there buttons in the UIAlertController you will not be able to press them
indicator.startAnimating()
ViewController.presentViewController(pending, animated: true, completion: nil)
}
and
func displayActivityAlertNoAnim(title: String, #ViewController: UIViewController)
{
let pending = UIAlertController(title: "\n\n\n"+title, message: nil, preferredStyle: .Alert)
//create an activity indicator
let indicator = UIActivityIndicatorView(frame: pending.view.bounds)
indicator.autoresizingMask = .FlexibleWidth | .FlexibleHeight
indicator.color = UIColor(rgba: Palette.accent)
//add the activity indicator as a subview of the alert controller's view
pending.view.addSubview(indicator)
pending.view.backgroundColor = UIColor.whiteColor()
// this line cause the alert controller to become full width of the screen
indicator.userInteractionEnabled = false // required otherwise if there buttons in the UIAlertController you will not be able to press them
indicator.startAnimating()
ViewController.presentViewController(pending, animated: **false**, completion: nil)
}
Code for checking class and dismissing:
if self.presentedViewController!.isKindOfClass(UIAlertController){
self.dismissViewControllerAnimated(true, completion: nil)
}

Answer 1

You need to make use of the completion parameter in presentViewController(). This is a closure which will get executed exactly after the UIAlertController has become visible on the screen.
Now, I can only provide you with some pseudocode since you haven't provided any code on how you download or the callback you receive after downloading, but try something like the following:
func displayActivityAlert(title: String, #ViewController: UIViewController) {
let pending = UIAlertController(title: "\n\n\n"+title, message: nil, preferredStyle: .Alert)
...
ViewController.presentViewController(pending, animated: true) { () -> Void in
// Start downloading from webservice
}
}
And dismissing:
if self.presentedViewController!.isKindOfClass(UIAlertController){
self.dismissViewControllerAnimated(true) { () -> Void in
// Perform segue to tableview
}
}
UPDATE 1:
Updated pseudocode based on OP's architecture.
If you have factorised the code for your alerts into a separate file, then simply pass in the completion handler as a parameter like so:
func displayActivityAlert(title: String, #ViewController: UIViewController, completionHandler: ()->() ) {
let pending = UIAlertController(title: "\n\n\n"+title, message: nil, preferredStyle: .Alert)
...
self.presentViewController(pending, animated: true, completion: completionHandler)
}
And then whenever you call displayActivityAlert, then simply specify the callback, for example like so:
override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)
displayActivityAlert("Hello", ViewController: self) { () -> () in
// Download from webservice
}
}

Answer 2

simple code modify as you need
put this code inside a function or inside a button of action
will have a single button "OK"
let alertView = UIAlertController(title: "Your ERROR Heading!", message: "Your error message here", preferredStyle: .Alert)
let OKAction = UIAlertAction(title: "OK", style: .Default, handler: nil)
alertView.addAction(OKAction)
self.presentViewController(alertView, animated: true, completion: nil)

Answer 3

class func alertController(_ title:String, message: String, okTitle: String,cancelTitle: String? = nil,cancelCompletion:(() ->Void)? = nil, okCompletion :(() -> Void)?) {
let alertController = UIAlertController.init(title: title as String, message: message as String, preferredStyle: UIAlertControllerStyle.alert)
let okAction = UIAlertAction.init(title: okTitle as String, style: UIAlertActionStyle.default) { (alertAction :UIAlertAction) in
if okCompletion != nil{
okCompletion!()
}
}
alertController.addAction(okAction)
if cancelTitle != nil && !(cancelTitle?.isEmpty)!{
let cancelAction = UIAlertAction.init(title: cancelTitle, style: UIAlertActionStyle.cancel) { (alertAction : UIAlertAction) in
if cancelCompletion != nil{
cancelCompletion!()
}
}
alertController.addAction(cancelAction)
}
Constant.Common.APPDELObj.navVC?.visibleViewController?.present(alertController, animated: true, completion: nil)
}