2

我需要在后台执行一些计算。这是正确的方法吗？

重要请参阅 onPerformBackgroundTask。方法的第一部分结束了后台任务。是否有可能在应用程序暂停之前调用方法的第二部分？

- (void)applicationDidEnterBackground:(UIApplication *)application {  
[application endBackgroundTask:bgTask];
bgTask = UIBackgroundTaskInvalid; 

if ([self isNeedTimeToFinishTask]) 
{        
    bgTask = [application beginBackgroundTaskWithExpirationHandler:^{
        [application endBackgroundTask:bgTask];
        bgTask = UIBackgroundTaskInvalid;
    }];

    if (!backgroundTimer) 
    {
        self.backgroundTimer = [NSTimer scheduledTimerWithTimeInterval:540 target:self selector:@selector(onPerformBackgroundTask:) userInfo:nil repeats:YES];
    }
}

 -(void) onPerformBackgroundTask:(id) sender
{
 [[UIApplication sharedApplication] endBackgroundTask:bgTask];
 bgTask = UIBackgroundTaskInvalid; 

 if ([self isNeedTimeToFinishTask]) 
 {
    bgTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
        [[UIApplication sharedApplication] endBackgroundTask:bgTask];
        bgTask = UIBackgroundTaskInvalid;
    }];
 }
}

-(void) endBackgroundTask
{
 if ([backgroundTimer isValid]) 
 {
    [backgroundTimer invalidate];
    [backgroundTimer release];
 }    
 [[UIApplication sharedApplication] endBackgroundTask:bgTask];
 bgTask = UIBackgroundTaskInvalid;
}
4

0 回答 0