Repo created

iphone/Maps/Core/BackgroundFetchScheduler/BackgroundFetchScheduler.swift

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+@objc(MWMBackgroundFetchScheduler)
+final class BackgroundFetchScheduler: NSObject {
+  typealias FetchResultHandler = (UIBackgroundFetchResult) -> Void
+
+  private let completionHandler: FetchResultHandler
+  private let tasks: [BackgroundFetchTask]
+  private var tasksLeft: Int
+  private var bestResultSoFar = UIBackgroundFetchResult.noData
+
+  @objc init(tasks: [BackgroundFetchTask], completionHandler: @escaping FetchResultHandler) {
+    self.tasks = tasks
+    self.completionHandler = completionHandler
+    tasksLeft = tasks.count
+    super.init()
+  }
+
+  @objc func run() {
+    fullfillFrameworkRequirements()
+
+    let completionHandler: FetchResultHandler = { [weak self] result in
+      self?.finishTask(result: result)
+    }
+
+    tasks.forEach { $0.start(completion: completionHandler) }
+  }
+
+  private func fullfillFrameworkRequirements() {
+    minFrameworkTypeRequired().create()
+  }
+
+  private func minFrameworkTypeRequired() -> BackgroundFetchTaskFrameworkType {
+    return tasks.reduce(.none) { max($0, $1.frameworkType) }
+  }
+
+  private func finishTask(result: UIBackgroundFetchResult) {
+    updateFetchResult(result)
+    tasksLeft -= 1
+    if tasksLeft <= 0 {
+      completionHandler(bestResultSoFar)
+    }
+  }
+
+  private func updateFetchResult(_ result: UIBackgroundFetchResult) {
+    if resultPriority(bestResultSoFar) < resultPriority(result) {
+      bestResultSoFar = result
+    }
+  }
+
+  private func resultPriority(_ result: UIBackgroundFetchResult) -> Int {
+    switch result {
+      case .newData: return 3
+      case .noData: return 1
+      case .failed: return 2
+      @unknown default: fatalError("Unexpected case in UIBackgroundFetchResult switch")
+    }
+  }
+}