access methods from protocols to viewcontroller - swift3

Question

I was just implementing object class to access methods and protocols. Following
import UIKit
import Foundation
import Alamofire
import SVProgressHUD
protocol ParseAPIProtocol:class {
func APIresponse(responseDict: NSDictionary)
}
class ParseAPI :NSObject{
// weak var mydelegate : MyProtocols?
weak var delegateAPI:ParseAPIProtocol?
class func ParseUrl(postparameters: [String: AnyObject]!, url:String, current:UIViewController) {
print(postparameters)
print(url)
SVProgressHUD.show()
Alamofire.request(url, method: .post, parameters: postparameters, encoding: URLEncoding.default, headers: nil).responseJSON
{
(response:DataResponse<Any>) in
switch(response.result)
{
case .success(_):
if response.result.value != nil
{
let jsonResult = (try! JSONSerialization.jsonObject(with: response.data!, options: JSONSerialization.ReadingOptions.mutableContainers)) as! NSDictionary
print(jsonResult)
}
break
case .failure(_):
SVProgressHUD.dismiss()
print(response.result.error as Any)
break
}
}
}
Whenever I got the jsonResult, I just want to call fun APIresponse to parse result dictionary to viewcontroller class.
I declared the method on viewcontroller and its delegate.
But when I tried to call protocol method, it doesn't give me access to the method. May be I am doing something wrong. Please look into my method.
Thanks!

Answer 1

The way I see it there are several issues, although it's hard to tell because you don't show the relevant code in your view controller
(how you set up the delegate, how you call your parse API).
First, you never call your delegate with the result. With your current setup this isn't even possible: you define ParseAPI to have a
delegate (instance) member but define ParseUrl as a class func. I guess this is what you meant when saying "it doesn't give me access to the method".
Try defining it as a member function and then, in the success case call the delegate:
self.delegateAPI?.APIresponse(responseDict: jsonResult)
In your view controller, instantiate a ParseAPI instance and keep it alive (for example by storing it in a strong instance member), set its delegate,
and call ParseUrl(...). This call will return pretty much immediately and later, when the request and response is handled, your delegate method will
be called.
class ViewController: UIViewController, ParseAPIProtocol
{
var parser: ParseAPI?
func somewhere()
{
self.parser = ParseAPI()
self.parser!.delegateAPI = self
self.parser!.ParseUrl(postparameters: [:], url: "...", current: self)
}
func APIresponse(responseDict: NSDictionary)
{
print("VC got response:", responseDict)
}
}
Second, the current parameter is never used, you can remove it. Either that or you can remove the whole delegate thing and replace the current parameter
with a callback, something like this:
func ParseUrl(postparameters: [String: AnyObject]!, url:String, finished: #escaping (_ response: NSDictionary?) -> Void)
{
...
// success case:
finished(jsonResult)
// failure case:
finished(nil)
}
and call it like this:
self.parser!.ParseUrl(postparameters: [:], url: "...", finished: { (response: NSDictionary?) in
// handle response
})
You can also define your callback to have an error parameter so you can act accordingly when one occurs.
And finally, while I don't know SVProgressHUD, you probably wanna call SVProgressHUD.dismiss() in the success case, too.