Question

即使用户最小化了应用，我也需要在应用中运行NSTimer。计时器用于每隔15秒点击一次Web服务，4分钟后我需要执行某些导航。怎么办呢？

我知道此问题也已提前提出，但我未能找到合适的答案。

Answer 1

你需要一个可能的理由。如果它适用于导航应用程序，VOIP，或仅用于后台下载（在某些情况下），则可能。但除此之外，你不能这样做。

Answer 2

在继续之前，请考虑为什么当应用程序在后台运行时，运行计时器并不容易。这是因为它清空了手机的电池。如果你这样做，你会得到不满意的顾客。哪个苹果公司并不在乎，但苹果公司得到了不满意的顾客，他们非常关心这些顾客。在设置 - ＆gt;下电池Apple将告诉用户哪个应用程序在过去24小时/ 6天内使用了多少能量，因此人们可以找到您的应用程序，如果它在后台浪费能源并将其丢弃。

Answer 3

您可以将应用配置为在后台运行，但无法控制iOS在后台调用应用的频率。

我知道这是一个非常糟糕的解决方案和滥用服务，但您可以启动后台文件下载并使您的服务器发送数据的速度非常慢，大约需要4分钟。传输完成后，iOS将向您的应用报告。如果您的应用未终止，iOS也会向您的应用报告下载进度。但如果应用程序不在前台，则无法在传输完成时打开应用程序。

使用创建配置对象   backgroundSessionConfigurationWithIdentifier：方法   NSURLSessionConfiguration。

设置配置对象的值   sessionSendsLaunchEvents属性为YES。

如果您的应用开始转移   虽然它在前台，但建议你也设置   配置对象的自由选择属性为YES。

配置   适当的配置对象的任何其他属性。

使用   用于创建NSURLSession对象的配置对象。

当与后台会话关联的所有任务都是   完成后，系统重新启动已终止的应用程序（假设是   sessionSendsLaunchEvents属性设置为YES，用户确实如此   不强制退出应用程序）并调用应用程序委托   应用：handleEventsForBackgroundURLSession：completionHandler：   方法

https://developer.apple.com/library/ios/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/BackgroundExecution/BackgroundExecution.html

Answer 4

AppDelegate.h //使用本地通知获取一些函数调用

 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{
 [self getNotificationPermission];
return YES;
}

此方法用于许可

-(void)getNotificationPermission{

// Accept Action

UIMutableUserNotificationAction *acceptAction = [[UIMutableUserNotificationAction alloc] init];
acceptAction.identifier = @"Accept";
acceptAction.title = @"Yes i am OK";
acceptAction.activationMode = UIUserNotificationActivationModeBackground;
acceptAction.destructive = NO;
acceptAction.authenticationRequired = NO;

// Reject Action

UIMutableUserNotificationAction *rejectAction = [[UIMutableUserNotificationAction alloc] init];
rejectAction.identifier = @"Reject";
rejectAction.title = @"On i am Not OK";
rejectAction.activationMode = UIUserNotificationActivationModeBackground;
rejectAction.destructive = YES;
rejectAction.authenticationRequired = YES;

// Reply Action

UIMutableUserNotificationAction *replyAction = [[UIMutableUserNotificationAction alloc] init];
replyAction.identifier = @"Reply";
replyAction.title = @"Reply";
replyAction.activationMode = UIUserNotificationActivationModeForeground;
replyAction.destructive = NO;
replyAction.authenticationRequired = YES;

// Email Category

UIMutableUserNotificationCategory *emailCategory = [[UIMutableUserNotificationCategory alloc] init];
emailCategory.identifier = @"Email";
[emailCategory setActions:@[acceptAction,rejectAction,replyAction] forContext:UIUserNotificationActionContextDefault];
[emailCategory setActions:@[acceptAction,rejectAction] forContext:UIUserNotificationActionContextMinimal];

// Download Action

UIMutableUserNotificationAction *downloadAction = [[UIMutableUserNotificationAction alloc] init];
downloadAction.identifier = @"Download";
downloadAction.title = @"Download";
downloadAction.activationMode = UIUserNotificationActivationModeForeground;
downloadAction.destructive = NO;
downloadAction.authenticationRequired = YES;

UIMutableUserNotificationAction *cancelAction = [[UIMutableUserNotificationAction alloc] init];
cancelAction.identifier = @"Cancel";
cancelAction.title = @"Cancel";
cancelAction.activationMode = UIUserNotificationActivationModeForeground;
cancelAction.destructive = YES;
cancelAction.authenticationRequired = YES;


// Image Category

UIMutableUserNotificationCategory *imageCategory = [[UIMutableUserNotificationCategory alloc] init];
imageCategory.identifier = @"Image";
[imageCategory setActions:@[downloadAction,cancelAction] forContext:UIUserNotificationActionContextDefault];
[imageCategory setActions:@[downloadAction,cancelAction] forContext:UIUserNotificationActionContextMinimal];


NSSet *categories = [NSSet setWithObjects:emailCategory,imageCategory, nil];
UIUserNotificationType notificarionType = UIUserNotificationTypeBadge | UIUserNotificationTypeSound | UIUserNotificationTypeAlert;

// Register notification types and categories
UIUserNotificationSettings *notificationSettings = [UIUserNotificationSettings settingsForTypes:notificarionType categories:categories];
[[UIApplication sharedApplication] registerUserNotificationSettings:notificationSettings];

// This line of code is required for remote push notification
//[[UIApplication sharedApplication] registerForRemoteNotifications];
}
-(void)application:(UIApplication *)application didRegisterUserNotificationSettings:(UIUserNotificationSettings *)notificationSettings{

//UIUserNotificationType notificationtype = [notificationSettings types];

}

// You can check the current user notifiartions settings whenever you need it
 -(void)getReadyForNotification{

//UIUserNotificationSettings *settings = [[UIApplication sharedApplication] currentUserNotificationSettings];
//[self checkSettings:settings];
}

// When appliation is in foregrounf this methid will get caled if you have scheduled a local notification
-(void)application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification{

//CLRegion *region = notification.region;
if ([notification.category isEqualToString:@"Image"]) {
    NSLog(@"Image category notification is presented to the user");
}else if([notification.category isEqualToString:@"Email"]){
    NSLog(@"Email category notification is presented to the user");
}
}

-(void)application:(UIApplication *)application handleActionWithIdentifier:(NSString *)identifier forLocalNotification:(UILocalNotification *)notification completionHandler:(void (^)())completionHandler{

if ([identifier isEqualToString:@"Accept"]) {
    [self printAlert:@"Accept"];
}else if ([identifier isEqualToString:@"Reject"]) {
    [self printAlert:@"Reject"];
}else if ([identifier isEqualToString:@"Reply"]) {
    [self printAlert:@"Reply"];
}else if ([identifier isEqualToString:@"Download"]) {
    [self printAlert:@"Download"];
}else if ([identifier isEqualToString:@"Cancel"]) {
    [self printAlert:@"Cancel"];
}
completionHandler();
}

-(void)printAlert:(NSString *)title
{
NSLog(@"%@ button is selected",title);
if ([title isEqualToString:@"Accept"])
{
}
else if ([title isEqualToString:@"Reject"])
{
}


}

// Callback for remote notification
-(void)application:(UIApplication *)application handleActionWithIdentifier:(NSString *)identifier forRemoteNotification:(NSDictionary *)userInfo completionHandler:(void (^)())completionHandler{
NSLog(@"handleActionWithIdentifier forRemoteNotification");
}

在ViewController上设置本地通知

UILocalNotification* localNotification = [[UILocalNotification alloc] init];
localNotification.fireDate = [NSDate dateWithTimeIntervalSinceNow:10];
localNotification.alertBody = @"How you are Feeling Today ?";
localNotification.category = @"Email";  // This should match categories identifier which we have defined in App delegate
[[UIApplication sharedApplication] scheduleLocalNotification:localNotification];

使用此代码，如果用户在前景中选择通知，则在每个周期的时间段内获取本地通知，然后在您想要的特定阶段或屏幕中打开应用。这段代码也没有违反苹果指南。

在后台执行NSTimer

4 个答案: