Background Fetchが動作しない

###前提・実現したいこと
iPhone7の実機でBackground Fetchを試したい
XcodeのデバッグエリアにBackground Fetchが呼出されたときの時刻を出力する

###発生している問題・エラーメッセージ

1時間ほど待ってもデバッグエリアに日付が出力されない。

###該当のソースコード AppDelegate.swift

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?
    
    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        application.setMinimumBackgroundFetchInterval(UIApplicationBackgroundFetchIntervalMinimum)
        return true
    }
    
    func application(application: UIApplication, performFetchWithCompletionHandler completionHandler: (UIBackgroundFetchResult) -> Void) {
        // 処理を実装
        print(Date())
        completionHandler(UIBackgroundFetchResult.newData)
    }

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        return true
    }

    func applicationWillResignActive(_ application: UIApplication) {
        // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
        // Use this method to pause ongoing tasks, disable timers, and invalidate graphics rendering callbacks. Games should use this method to pause the game.
    }

    func applicationDidEnterBackground(_ application: UIApplication) {
        // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
        // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
    }

    func applicationWillEnterForeground(_ application: UIApplication) {
        // Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
    }

    func applicationDidBecomeActive(_ application: UIApplication) {
        // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
    }

    func applicationWillTerminate(_ application: UIApplication) {
        // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
    }


}

###試したこと
課題に対してアプローチしたことを記載してください

###補足情報(言語/FW/ツール等のバージョンなど)
info.plistなどの設定は済んでいます。

行動規範の内容に同意します

回答2件

自分も経験したのですが、Background Fetchは驚くほど実行されません。
UIApplicationBackgroundFetchIntervalMinimumを設定していても、12時間以上実行されないこともあります。
デバッグ実行でとりあえず「Background Fetchが呼出されたときの時刻を出力」されたいのであれば、
"Edit Scheme">"Options">"Background Fetch"にチェックを入れたうえで
"Debug">"Simulate Background Fetch"でBackground Fetchを疑似的に発生させる必要があります。

以下のサイトが参考になります。

投稿2016/12/31 08:49