Swift Progress View Value Passed Around Functions - ios

Question

I am needing to implement a progress bar that takes into account a couple of factors.
I have three different classes, my ViewController, a Networking class to handle the network calls and a dataManager class to handle all the db operations.
Now my progressView lives in my viewcontroller and I am looking at a way of updating it as each of the different operations are performed in the other classes.
I am using Alamofire so I know I can use .progress{} to catch the value of the JSON progress but that would also mean exposing the ViewController to the Networking class, which I assume is bad practice?
I think this should be achieved using completion handlers but as I have already setup another thread for handling the JSON / DB operation I'm not wanting to over complicate it anymore than I need to
Networking:
func makeGetRequest(url : String, params : [String : String]?, completionHandler: (responseObject: JSON?, error: NSError?) -> ()) -> Request? {
return Alamofire.request(.GET, url, parameters: params, encoding: .URL)
.progress { _, _, _ in
//bad practice?
progressView.setProgress(request.progress.fractionCompleted, animated: true)
}
.responseJSON { request, response, data, error in completionHandler(
responseObject:
{
let json = JSON(data!)
if let anError = error
{
println(error)
}
else if let data: AnyObject = data
{
let json = JSON(data)
}
return json
}(),
error: error
)
}
}
ViewController:
dataManager.loadData({(finished: Bool, error:NSError?) -> Void in
if let errorMessage = error{
self.syncProgress.setProgress(0, animated: true)
let alertController = UIAlertController(title: "Network Error", message:
errorMessage.localizedDescription, preferredStyle: UIAlertControllerStyle.Alert)
alertController.addAction(UIAlertAction(title: "Dismiss", style: UIAlertActionStyle.Default,handler: nil))
self.presentViewController(alertController, animated: true, completion: nil)
}
if finished{
for i in 0..<100 {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), {
sleep(1)
dispatch_async(dispatch_get_main_queue(), {
self.counter++
return
})
})
}
}
})
As you can see I am waiting on the finished boolean in the datamanger class to be set before updating the progress bar. The thing is, dataManager makes a call to networking and performs a bunch of other stuff before it finishes, it would be handy to update the progress bar along the way but I'm not sure of the best approach?
DataManager:
func loadData(completion: (finished: Bool, error: NSError?) -> Void) {
var jsonError: NSError?
networking.makeGetRequest(jobsUrl, params: nil) { json, networkError in
//....
}

Answer 1

I'm not too familiar with swift so I can't give you a code example but the way I would do this is create a protocol on your Networking class NetworkingDelegate and implement that protocol in your ViewController. The protocol method would be something like (in objective-c) NetworkingRequestDidUpdatProgress:(float progress)
This is assuming your ViewController calls Networking.makeGetRequest. If it's another class, you would implement the delegate in that class, or you could bubble up the delegate calls to your ViewController through the DataManager class.