Question

我的应用程序需要定期调用方法。

即使已将应用程序放在后台，也应该进行此调用。

应用程序可以在后台运行的时间是未定义的，只要应用程序可以从后台恢复即可。

我有一个管理计时器的课程：

@protocol TimerDelegate <NSObject>
- (void)startTimerAction:(id)userInfo;
@end

@interface TimerController : NSObject{
    NSTimer *repeatingTimer;
    id <TimerDelegate> delegate;
}
+ (TimerController *)sharedInstance;

- (void)startTimerForSender:(id <TimerDelegate>)sender withTimeInterval:(NSTimeInterval)time;
- (void)stopTimer;

@end

实现：

#import "TimerController.h"

TimerController *singletonInstance;

@implementation TimerController

#pragma mark - Singleton
+ (TimerController *)sharedInstance {

    if (singletonInstance == nil) {
        singletonInstance =  [[super allocWithZone:NULL] init];
    }
    return singletonInstance;
}

+ (id)allocWithZone:(NSZone *)zone
{
    return [self sharedInstance];
}

- (id)copyWithZone:(NSZone *)zone
{
    return self;
}

#pragma mark - Public
- (void)startTimerForSender:(id <TimerDelegate>)sender withTimeInterval:(NSTimeInterval)time
{
    if (repeatingTimer) {
        [self stopTimer];
    }

    if (sender) {
        delegate = sender;
    }

    if (time > 0.0) {
        NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:time target:self selector:@selector(targetMethod:)
                                                        userInfo:[self userInfo] repeats:YES];
        repeatingTimer = timer;
    }
}

- (void)stopTimer
{
    if (repeatingTimer) {
        [repeatingTimer invalidate];
        repeatingTimer = nil;
    }
}

- (NSDictionary *)userInfo
{
    return @{@"StartDate" : [NSDate date]};
}

- (void)targetMethod:(NSTimer*)theTimer
{
    if (delegate && [delegate respondsToSelector:@selector(startTimerAction:)]) {
        [delegate startTimerAction:[repeatingTimer userInfo]];
    }
}


@end

我以这种方式使用TimerController类：

-(void)viewDidLoad{
[super viewDidLoad]
TimerController *timerC = [TimerController sharedInstance];
[timerC startTimerForSender:self withTimeInterval:30];

}

#pragma mark - TimerDelegate

- (void)startTimerAction:(id)userInfo
{
NSLog(@"Method called");
}

我可以每隔30秒读入NSLog条目。将应用程序置于后台使定时器停止，并且当应用程序恢复计时器正常工作时，它不会每30秒写入一次日志。

我需要每隔30秒调用一次方法，尽管应用程序在后台。

我读到了这个问题：Timer in background mode

我必须能够向AppStore提交申请。

由于

Answer 1

- (void)applicationDidEnterBackground:(UIApplication *)application
{
    bgTask = [application beginBackgroundTaskWithExpirationHandler:^{
        // Clean up any unfinished task business by marking where you
        // stopped or ending the task outright.
        [application endBackgroundTask:bgTask];
        bgTask = UIBackgroundTaskInvalid;
    }];

    // Start the long-running task and return immediately.
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        // Do the work associated with the task, preferably in chunks.

        [application endBackgroundTask:bgTask];
        bgTask = UIBackgroundTaskInvalid;
    });
}

来源：iPhone Programmig Guide

类似的问题：https://stackoverflow.com/a/8613624/1827690

Answer 2

要在后台持续运行您的应用程序，您需要在plist 所需背景模式中注册您的应用

Documentation

iOS计时器在后台运行

2 个答案: