iOS防止程序被后台kill掉

项目有个需求，类似闹钟功能，当收到后台的推送消息后客户端连续播放提示语音并让手机开启振动，当中遇到了不少问题：

1、当应用一直保持在前台的情况下，收到推送消息后语音和振动可以正常触发
2、在第一条的基础上，语音和振动被触发后再按Home键进入后台，这时语音和振动都失效
3、当应用进入后台的情况下，收到推送消息后语音和振动都不能被触发

为解决这一问题，查了大量资料，并验证多遍，可以使用下列两种方法解决：

一、开启后台持续定位

1、设置Backgound Modes

788BFE1C-C1C6-4855-8B44-79878467EB51.png

2、在info.plist中设置

Privacy - Location Always Usage Description

3 、在didFinishLaunchingWithOptions中执行下面的initLocationManager方法

-(void)initLocationManager{
    //1.创建定位管理对象
    _manager = [[CLLocationManager alloc]init];

    //2.设置属性 distanceFilter、desiredAccuracy
    _manager.distanceFilter = kCLDistanceFilterNone;//实时更新定位位置
    _manager.desiredAccuracy = kCLLocationAccuracyBest;//定位精确度
    if([_manager respondsToSelector:@selector(requestAlwaysAuthorization)]){
        [_manager requestAlwaysAuthorization];
    }
    //该模式是抵抗程序在后台被杀，申明不能够被暂停
    _manager.pausesLocationUpdatesAutomatically = NO;
    _manager.allowsBackgroundLocationUpdates = YES;
    //3.设置代理
    _manager.delegate = self;
    //4.开始定位
    [_manager startUpdatingLocation];
    //5.获取朝向
    [_manager startUpdatingHeading];
}

//定位成功调用的的方法
-(void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations{

    // 获取位置信息
    CLLocation *newLocation=[locations lastObject];
    double lat = newLocation.coordinate.latitude;
    double lon = newLocation.coordinate.longitude;
    double alt = newLocation.altitude;
    NSLog(@"纬度:%f,经度:%f,海拔:%f",lat,lon,alt);
}

- (void)applicationWillResignActive:(UIApplication *)application {
    [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
    
    [self.manager startUpdatingLocation];
}

- (void)applicationDidEnterBackground:(UIApplication *)application {
    
    NSLog(@"进入后台");
    UIApplication *app = [UIApplication sharedApplication];
    __block  UIBackgroundTaskIdentifier bgTask;
    bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
        dispatch_async(dispatch_get_main_queue(), ^{
            
            if (bgTask != UIBackgroundTaskInvalid){
                bgTask = UIBackgroundTaskInvalid;
            }
        });
    }];
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        dispatch_async(dispatch_get_main_queue(), ^{
            if (bgTask != UIBackgroundTaskInvalid){
            bgTask = UIBackgroundTaskInvalid;
            }
        });
    });
    
   [self.manager startUpdatingLocation];
}

二、后台连续播放音乐的方法

1、设置Backgound Modes

F01AB26A-6E44-4F88-A70A-4CFE4D8A412B.png

2、在didFinishLaunchingWithOptions中执行下面的initPlayMusic方法

-(void)initPlayMusic{
  
    //先注册响应后台控制
    [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
    //处理中断事件的通知
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleInterreption:) name:AVAudioSessionInterruptionNotification object:[AVAudioSession sharedInstance]];
    
    //设置并激活音频会话类别
    AVAudioSession *session = [AVAudioSession sharedInstance];
    [session setCategory:AVAudioSessionCategoryPlayback error:nil];
    [session setActive:YES error:nil];
    
    //播放背景音乐
    NSString *musicPath = [[NSBundle mainBundle] pathForResource:@"紫藤花" ofType:@"mp3"];
    NSURL *url = [[NSURL alloc] initFileURLWithPath:musicPath];
    
    // 创建播放器
    _player = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:nil];
    [_player prepareToPlay];
    _player.volume = 1;
    _player.numberOfLoops = -1; //设置音乐播放次数  -1为一直循环
    [_player play]; //播放
}

//处理中断事件
-(void)handleInterreption:(NSNotification *)sender{
     NSLog(@"--1->%@",sender.userInfo);
    
    if(_isPlayed){
        [self.player pause];
        _isPlayed = NO;
    }else{
        [self.player play];
        _isPlayed = YES;
    }
}

//应用将要进入不活跃的状态
-(void)applicationWillResignActive:(UIApplication *)application{
    //开启后台处理多媒体事件
    [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
    AVAudioSession *session=[AVAudioSession sharedInstance];
    [session setActive:YES error:nil];
    //后台播放//这样做，可以在按home键进入后台后 ，播放一段时间，几分钟吧。但是不能持续播放网络歌曲，
    [session setCategory:AVAudioSessionCategoryPlayback error:nil];
    //若需要持续播放网络歌曲，还需要申请后台任务id，具体做法是：
    //其中的_bgTaskId是后台任务UIBackgroundTaskIdentifier _bgTaskId;
    _bgTaskId =[AppDelegate backgroundPlayerID:_bgTaskId];
}

//实现一下backgroundPlayerID:这个方法:
+(UIBackgroundTaskIdentifier)backgroundPlayerID:(UIBackgroundTaskIdentifier)backTaskId{
    
    //允许应用程序接收远程控制
    [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
    //设置后台任务ID
    UIBackgroundTaskIdentifier newTaskId = UIBackgroundTaskInvalid;
    newTaskId = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:nil];
    if(newTaskId!=UIBackgroundTaskInvalid&&backTaskId!=UIBackgroundTaskInvalid){
        [[UIApplication sharedApplication] endBackgroundTask:backTaskId];
    }
    return newTaskId;
}

以上两种方法经测试，可以一直在后台运行不会被kill掉