首先感谢你与AirFlow RAOP的惊人的作品是相当困难的事情!
所以你可以做的是
1.创建一个后台任务处理为dispatch_block_t,让我们说
dispatch_block_t myDummyBackgroundTaskBlock = {
[[UIApplication sharedApplication] endBackgroundTask:myDummyBackgroundTask];
myDummyBackgroundTask = UIBackgroundTaskInvalid;
myDummyBackgroundTask = [app beginBackgroundTaskWithExpirationHandler:myDummyBackgroundTask];
};
2.定义这个地方后台和前台任务的处理程序
// foreground
-(void)handleTasksForApplicationInForeground {
if(myDummyBackgroundTask) { // reset that task
[[UIApplication sharedApplication] endBackgroundTask: myDummyBackgroundTask];
myDummyBackgroundTask = UIBackgroundTaskInvalid;
}
}
// background
-(void) handleTasksForApplicationInBackground {
UIDevice *device = [UIDevice currentDevice];
BOOL backgroundSupported = NO;
if ([device respondsToSelector:@selector(isMultitaskingSupported)])
backgroundSupported = device.multitaskingSupported;
if(backgroundSupported && backgroundEnabled) { // perform a background task
myDummyBackgroundTaskBlock = ^{
[[UIApplication sharedApplication] endBackgroundTask: myDummyBackgroundTaskBlock];
myDummyBackgroundTaskBlock = UIBackgroundTaskInvalid;
};
SEL sel = @selector(doDummyBackgroundTask);
[self doBackgroundTaskAsync:sel];
[self performSelector:@selector(doBackgroundTaskAsync:) withObject:nil afterDelay:500.0f]; /// LP: this is the funny part since iOS will kill the task after 500 sec.
}
}
3.现在让我们来看看h andle在应用程序委托的背景模式(定义之前,你可以在应用的.plist激活与不同选项的背景模式):
-(void)applicationDidEnterBackground:(UIApplication *)application {
[self handleTasksForApplicationInBackground];
}
-(void)applicationWillEnterForeground:(UIApplication *)application {
[self handleTasksForApplicationInForeground];
}
4。让我们来看看背景的异步任务选择做什么
-(void) doBackgroundTaskAsync:(SEL)selector {
@try {
if([[UIApplication sharedApplication] backgroundTimeRemaining] < 5) {
return;
}
if(!myDummyBackgroundTaskBlock) { // need to create again on-the-fly
myDummyBackgroundTaskBlock = ^{
[[UIApplication sharedApplication] endBackgroundTask:myDummyBackgroundTask];
myDummyBackgroundTask = UIBackgroundTaskInvalid;
};
}
myDummyBackgroundTask = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:myDummyBackgroundTaskBlock];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
while ([[UIApplication sharedApplication] backgroundTimeRemaining] > 5.0) {
int delta = 5.0;
[self performSelector: selector ];
sleep(delta);
}
});
}
@catch (...) {
}
}
我知道,这个解决方案的工作很好,但我知道,有时它发生,iOS将反正杀应用程序的后台任务。无论如何,如果用户突然在前台和后台之间切换应用程序,它将无限期地工作。
非常感谢!我将用即将发布的版本对此进行测试。谢谢! – Trenskow 2013-04-20 10:36:49
从iOS7起,背景活动从600秒缩短。 (5分钟)至180秒。 (3分钟),所以调用doBackgroundTaskAsync(延迟*)的选择器必须在大于等于180.0f后被调用 – loretoparisi 2014-09-28 22:48:17