performFetchWithCompletionHandler 只被调用

Posted 2023-03-16

【中文标题】performFetchWithCompletionHandler 只被调用

【英文标题】：performFetchWithCompletionHandler only get called ones

【发布时间】：2013-09-02 19:03:15

【问题描述】：

这是我的应用委托

 (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions


    [[UIApplication sharedApplication] setMinimumBackgroundFetchInterval:2];

    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
    // Override point for customization after application launch.
    self.viewController = [[[ViewController alloc] initWithNibName:@"ViewController" bundle:nil] autorelease];
    UINavigationController *nav=[[[UINavigationController alloc]initWithRootViewController:self.viewController ] autorelease];
    nav.navigationBar.hidden=YES;
    self.window.rootViewController = nav;
    [self.window makeKeyAndVisible];
    return YES;


-(void)application:(UIApplication *)application performFetchWithCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler

    NSLog(@"########### Received Background Fetch ###########");
    //Download  the Content .

     [self sometask]; // i want to do some task here but this method get called only ones when i try to launch application 

    //Cleanup
    completionHandler(UIBackgroundFetchResultNoData);

所以问题是 是的，我已经在信息 pList 中完成了所有操作，但没有帮助，请提出一些建议

【问题讨论】：

问题将出现在您的函数“sometask”中，尝试通过注释行“[self sometask];”来运行它，我认为您使用“调试-> 模拟后台提取”选项正确模拟后台提取。 ,确保调用了CompletionHandler

我有同样的问题，只调用一次。

【参考方案1】：

请注意，仅当系统告诉您执行后台提取时才应调用此方法。

您可以在 Xcode 中进行模拟：