Custom message fetched from API in UIActivityViewController - ios

Question

I want my app users to share an link using an UIACtivityViewController. The link is not static and I have to fetch it from an api. I want to fetch this link as soon as someone presses a icon in UIActivityViewController but how I am doing it now is not working. The completionhandler of the request is always excuted at the end of the method fetchShareURL(). Could someone tell me how to fix this?
import UIKit
class ShareItemSource: NSObject, UIActivityItemSource {
var objects : [AnyObject]?
var shareURL : String?
init(objects : [AnyObject]?){
self.objects = objects
}
func fetchShareURL() -> Bool{
//fetch share url from api
let api = Api()
let semaphore = dispatch_semaphore_create(0);
let backgroundQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0)
dispatch_async(backgroundQueue, {
api.export(self.groupObjList, receiptObjList: self.receiptObjList){ status, message, url in
dispatch_async(dispatch_get_main_queue(), {
self.shareURL = url
dispatch_semaphore_signal(semaphore);
})
}
});
let delayInSeconds = 30.0;
let delayTime = dispatch_time(DISPATCH_TIME_NOW, Int64(delayInSeconds * Double(NSEC_PER_SEC)))
dispatch_semaphore_wait(semaphore, delayTime)
if self.shareURL != nil{
return true
} else {
return false
}
}
#objc func activityViewControllerPlaceholderItem(activityViewController: UIActivityViewController) -> AnyObject {
return ""
}
#objc func activityViewController(activityViewController: UIActivityViewController, itemForActivityType activityType: String) -> AnyObject? {
if fetchShareURL() == true{
return "Download files: "+self.shareURL!
} else {
return nil
}
}
func activityViewController(activityViewController: UIActivityViewController, subjectForActivityType activityType: String?) -> String {
return "title of share"
}
func activityViewController(activityViewController: UIActivityViewController, thumbnailImageForActivityType activityType: String?, suggestedSize size: CGSize) -> UIImage? {
//do stuff
}
}

Answer 1

If data to be provided in a UIActivityView takes time to provide, use a UIActivityItemProvider. It is an NSOperation subclass and solves the whole problem in a completely coherent way. Indeed, this sort of situation is exactly what it is intended for. (And watch the WWDC 2015 video on advanced NSOperation, please.)

Answer 2

Changed it to this for now. Later I'll use an NSOperation.
api.export(self.objects){ status, message, url in
if(status == true){
if let url = url{
alert.dismissViewControllerAnimated(true){
let sharingItems = ["Share url", url]
let activityViewController = UIActivityViewController(activityItems: [ShareItemSource(url: url)], applicationActivities: nil)
activityViewController.excludedActivityTypes = [UIActivityTypeAddToReadingList, UIActivityTypeCopyToPasteboard]
self.presentViewController(activityViewController, animated: true, completion: nil)
activityViewController.completionWithItemsHandler = { (activity, success, items, error) in
//Response
}
}
}
} else {
//handle fail
}
}