From 1adbed9f8b94521befd237c14d36325a55037a41 Mon Sep 17 00:00:00 2001
From: Nicholas Tay <nick@windblume.net>
Date: Sun, 17 Jul 2022 02:13:04 +1000
Subject: Experiment with async/await

Note that URLSession async only works >=iOS 15. I changed the target for
now, but may mess with continuations.
---
 foray/Fetchers/ForayFetcher.swift           | 27 +++++++++++----------------
 foray/Presenters/PenguinItemPresenter.swift | 19 ++++++++++---------
 foray/Scenes/ForayTableViewController.swift | 16 ++++++++++------
 3 files changed, 31 insertions(+), 31 deletions(-)

(limited to 'foray')

diff --git a/foray/Fetchers/ForayFetcher.swift b/foray/Fetchers/ForayFetcher.swift
index d8df037..e4c6fd9 100644
--- a/foray/Fetchers/ForayFetcher.swift
+++ b/foray/Fetchers/ForayFetcher.swift
@@ -27,23 +27,18 @@ class ForayFetcher {
         return jd
     }()
     
-    func fetch<T: Decodable>(url: String,
-                             receiver: @escaping (T) -> ()) {
-        // Fetch on a background thread
-        DispatchQueue.global(qos: .background).async {
-            var request = URLRequest(url: URL(string: url)!)
-            request.cachePolicy = .reloadRevalidatingCacheData // Needed otherwise default caching policy seems not to check properly
-            
-            // Basic auth if required
-            if (self.basicUsername != nil && self.basicPassword != nil) {
-                let authData = (self.basicUsername! + ":" + self.basicPassword!).data(using: .utf8)!.base64EncodedString()
-                request.addValue("Basic \(authData)", forHTTPHeaderField: "Authorization")
-            }
+    func fetch<T: Decodable>(url: String) async throws -> T {
+        var request = URLRequest(url: URL(string: url)!)
+        request.cachePolicy = .reloadRevalidatingCacheData // Needed otherwise default caching policy seems not to check properly
 
-            URLSession.shared.dataTask(with: request, completionHandler: { data, response, error -> Void in
-                let items = try! self.jsonDecoder.decode(T.self, from: data!)
-                receiver(items)
-            }).resume()
+        // Basic auth if required
+        if (self.basicUsername != nil && self.basicPassword != nil) {
+            let authData = (self.basicUsername! + ":" + self.basicPassword!).data(using: .utf8)!.base64EncodedString()
+            request.addValue("Basic \(authData)", forHTTPHeaderField: "Authorization")
         }
+
+        let (data, _) = try await URLSession.shared.data(for: request)
+        let items = try jsonDecoder.decode(T.self, from: data)
+        return items
     }
 }
diff --git a/foray/Presenters/PenguinItemPresenter.swift b/foray/Presenters/PenguinItemPresenter.swift
index c4553ae..1d617bf 100644
--- a/foray/Presenters/PenguinItemPresenter.swift
+++ b/foray/Presenters/PenguinItemPresenter.swift
@@ -8,18 +8,19 @@
 import Foundation
 
 class PenguinItemPresenter {
+
+    private struct Constants {
+        static let apiEndpoint = "https://users.windblume.net/~nick/upload/dummy.json"
+    }
     
     let fetcher = ForayFetcher()
     
-    func fetch(receiver: @escaping ([PenguinItemViewModel]) -> ()) {
-        fetcher.fetch(url: "https://users.windblume.net/~nick/upload/dummy.json") { [weak self] (apiItems: [PenguinItemModel]) in
-            // Callback to main thread here
-            // There probably is a nicer way to do it, but we will DispatchQueue it back
-            // from the Presenter-level for now (main thread from VC onwards)
-            DispatchQueue.main.async {
-                guard let self = self else { return }
-                receiver(self.transform(models: apiItems))
-            }
+    func fetch() async -> [PenguinItemViewModel] {
+        do {
+            let apiItems: [PenguinItemModel] = try await fetcher.fetch(url: Constants.apiEndpoint)
+            return transform(models: apiItems)
+        } catch {
+            return []
         }
     }
     
diff --git a/foray/Scenes/ForayTableViewController.swift b/foray/Scenes/ForayTableViewController.swift
index a29088c..849553c 100644
--- a/foray/Scenes/ForayTableViewController.swift
+++ b/foray/Scenes/ForayTableViewController.swift
@@ -42,21 +42,25 @@ class ForayTableViewController: UITableViewController, Coordinated {
         self.refreshControl?.addTarget(self, action: #selector(doRefresh), for: UIControl.Event.valueChanged)
     }
     
-    @objc func doRefresh(sender: AnyObject) {
+    @objc
+    func doRefresh(sender: AnyObject) {
         reloadApiData()
     }
     
     func reloadApiData() {
-        presenter.fetch { [weak self] (data: [PenguinItemViewModel]) in
-            guard let self = self else { return }
-            
-            let groups = Dictionary(grouping: data) { $0.year }
+        Task(priority: .medium) { [weak self] in
+            let models = await self?.presenter.fetch()
+
+            guard let self = self,
+                  let models = models else { return }
+
+            let groups = Dictionary(grouping: models) { $0.year }
             self.sections = groups.map { (key, values) in
                 return YearSection(year: key, items: values)
             }
             // Sort the sections from oldest year to newest
             self.sections.sort { (lhs, rhs) in lhs.year < rhs.year }
-            
+
             self.tableView.reloadData()
             self.refreshControl?.endRefreshing()
             self.coordinator?.hideLoading()
-- 
cgit