UIEvent
A UIEvent object (or, simply, an event object) represents an event in iOS. There are three general types of event: **touch events, motion events, and remote-control events ** Remote-control events allow a responder object to receive commands from an external accessory or headset so that it can manage manage audio and video—for example, playing a video or skipping to the next audio track. Motion events were introduced in iOS 3.0 and remote-control events in iOS 4.0.

Overview
A touch type of event object contains one or more touches (that is, finger gestures on the screen) that have some relation to the event. A touch is represented by a UITouch object. When a touch event occurs, the system routes it to the appropriate responder and passes in the UIEvent object in a message invoking a UIResponder method such as touchesBegan:withEvent:. The responder can then evaluate the touches for the event or for a particular phase of the event and handle them appropriately. The methods of UIEvent allow you to obtain all touches for the event (allTouches) or only those for a given view or window (touchesForView: or touchesForWindow:). It can also distinguish an event object from objects representing other events by querying an object for the time of its creation (timestamp).
A UIEvent object representing a touch event is persistent throughout a multi-touch sequence; UIKit reuses the same UIEvent instance for every event delivered to the application. You should never retain an event object or any object returned from an event object. If you need to keep information from an event around from one phase to another, you should copy that information from the UITouch or UIEvent object.
You can obtain event types and subtypes from the type and subtype properties. UIEvent defines event types for touch, motion, and remote-control events. It also defines a motion subtype for "shake” events and a series of subtype constants for remote-control events, such as “play” and “previous track.” The first responder or any responder in the responder chain implements the motion-related methods of UIResponder (such as motionBegan:withEvent:) to handle shaking-motion events. To handle remote-control events, a responder object must implement the remoteControlReceivedWithEvent: method of UIResponder.
The touchesForGestureRecognizer: method, which was introduced in iOS 3.2, allows you to query a gesture-recognizer object (an instance of a subclass of UIGestureRecognizer) for the touches it is currently handling.

typedef NS_ENUM(NSInteger, UIEventType) {
    UIEventTypeTouches,
    UIEventTypeMotion,
    UIEventTypeRemoteControl,
    UIEventTypePresses NS_ENUM_AVAILABLE_IOS(9_0),
};

typedef NS_ENUM(NSInteger, UIEventSubtype) {
    // 不包含任何子事件类型
    UIEventSubtypeNone                              = 0,
    
    // 摇晃事件（从iOS3.0开始支持此事件）
    UIEventSubtypeMotionShake                       = 1,
    
    //远程控制子事件类型（从iOS4.0开始支持远程控制事件）
    //播放事件【操作：停止状态下，按耳机线控中间按钮一下】
    UIEventSubtypeRemoteControlPlay                 = 100,
    //暂停事件
    UIEventSubtypeRemoteControlPause                = 101,
    //停止事件
    UIEventSubtypeRemoteControlStop                 = 102,
    //播放或暂停切换【操作：播放或暂停状态下，按耳机线控中间按钮一下】
    UIEventSubtypeRemoteControlTogglePlayPause      = 103,
    //下一曲【操作：按耳机线控中间按钮两下】
    UIEventSubtypeRemoteControlNextTrack            = 104,
    //上一曲【操作：按耳机线控中间按钮三下】
    UIEventSubtypeRemoteControlPreviousTrack        = 105,
    //快退开始【操作：按耳机线控中间按钮三下不要松开】
    UIEventSubtypeRemoteControlBeginSeekingBackward = 106,
    //快退停止【操作：按耳机线控中间按钮三下到了快退的位置松开】
    UIEventSubtypeRemoteControlEndSeekingBackward   = 107,
    //快进开始【操作：按耳机线控中间按钮两下不要松开】
    UIEventSubtypeRemoteControlBeginSeekingForward  = 108,
    //快进停止【操作：按耳机线控中间按钮两下到了快进的位置松开】
    UIEventSubtypeRemoteControlEndSeekingForward    = 109,
};

@interface UIEvent : NSObject
@property(nonatomic,readonly) UIEventType     type NS_AVAILABLE_IOS(3_0);
@property(nonatomic,readonly) UIEventSubtype  subtype NS_AVAILABLE_IOS(3_0);
@property(nonatomic,readonly) NSTimeInterval  timestamp;
@property(nonatomic, readonly, nullable) NSSet <UITouch *> *allTouches;
- (nullable NSSet <UITouch *> *)touchesForWindow:(UIWindow *)window;
- (nullable NSSet <UITouch *> *)touchesForView:(UIView *)view;
- (nullable NSSet <UITouch *> *)touchesForGestureRecognizer:(UIGestureRecognizer *)gesture NS_AVAILABLE_IOS(3_2);

// An array of auxiliary UITouch’s for the touch events that did not get delivered for a given main touch. This also includes an auxiliary version of the main touch itself.
- (nullable NSArray <UITouch *> *)coalescedTouchesForTouch:(UITouch *)touch NS_AVAILABLE_IOS(9_0);

// An array of auxiliary UITouch’s for touch events that are predicted to occur for a given main touch. These predictions may not exactly match the real behavior of the touch as it moves, so they should be interpreted as an estimate.
- (nullable NSArray <UITouch *> *)predictedTouchesForTouch:(UITouch *)touch NS_AVAILABLE_IOS(9_0);

Shake to play systemSound using AudioToolBox.framework

static void AudioServicesSystemSoundCompletionCall(SystemSoundID ssID, void* __nullable clientData){
    NSLog(@"声音播放完成");
}
-(void)motionBegan:(UIEventSubtype)motion withEvent:(UIEvent *)event{
    NSLog(@"摇动开始");
    
    //播放文件路径
    NSString *pathStr = [[NSBundle mainBundle]pathForResource:@"59" ofType:@"m4a"];
    NSURL *sourURL = [NSURL fileURLWithPath:pathStr];
    //注册系统音频ID
    SystemSoundID soundId;
    
    AudioServicesCreateSystemSoundID((__bridge CFURLRef)sourURL, &soundId);
//    AudioServicesPlaySystemSoundWithCompletion(soundId, ^{
//        AudioServicesDisposeSystemSoundID(soundId);
//    });
    //or
    AudioServicesAddSystemSoundCompletion(soundId, NULL, NULL, AudioServicesSystemSoundCompletionCall, (__bridge void *)self);
    AudioServicesPlaySystemSound(soundId);
}


-(void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event{
    NSLog(@"摇动结束");
}
-(void)motionCancelled:(UIEventSubtype)motion withEvent:(UIEvent *)event{
    if (event.subtype == UIEventSubtypeMotionShake) {
        NSLog(@"摇动取消");
    }
}

RemoteControlEvents

//为了模拟一个真实的播放器，程序中我们启用了后台运行模式，配置方法：在info.plist中添加UIBackgroundModes并且添加一个元素值为audio。
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  
    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:nil];
    if(![[AVAudioSession sharedInstance] setActive:YES error:nil])
    {
        NSLog(@"Failed to set up a session.");
    }
    [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];

    // Override point for customization after application launch.
    return YES;
}
- (void)viewDidLoad {
    [super viewDidLoad];
      _player = [[AVPlayer alloc]initWithURL:[NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"小苹果" ofType:@"mp3"]]];
    [_player play];
}
#pragma mark =====3 线控
//配置方法：在info.plist中添加UIBackgroundModes并且添加一个元素值为audio。
-(BOOL)canBecomeFirstResponder{
    return YES;
}
-(void)remoteControlReceivedWithEvent:(UIEvent *)event{
    
    if (event.type == UIEventTypeRemoteControl) {
        switch (event.subtype) {
            case UIEventSubtypeRemoteControlPlay:{
                NSLog(@"play---------");

            }break;
            case UIEventSubtypeRemoteControlPause:{
                NSLog(@"Pause---------");
            }break;
            case UIEventSubtypeRemoteControlStop:{
                NSLog(@"Stop---------");
            }break;
            case UIEventSubtypeRemoteControlTogglePlayPause:{
                //单击暂停键：103
                NSLog(@"单击暂停键：103");
                static int a = 0;
                a++;
                if (a%2 == 1) {
                    [_player pause];
                }else{
                    [_player play];
                }
            }break;
            case UIEventSubtypeRemoteControlNextTrack:{
                //双击暂停键：104
                NSLog(@"双击暂停键：104");
            }break;
            case UIEventSubtypeRemoteControlPreviousTrack:{
                NSLog(@"三击暂停键：105");
            }break;
            case UIEventSubtypeRemoteControlBeginSeekingForward:{
                NSLog(@"单击，再按下不放：108");
            }break;
            case UIEventSubtypeRemoteControlEndSeekingForward:{
                NSLog(@"单击，再按下不放，松开时：109");
            }break;
            default:
                break;
        }
    }
}
    

Insert earphone or pull out headphones

- (void)viewDidLoad {
    [super viewDidLoad];
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(audioRouteChangeListenerCallback:)   name:AVAudioSessionRouteChangeNotification object:nil];//设置通知
}
//通知方法的实现
- (void)audioRouteChangeListenerCallback:(NSNotification*)notification
{
    
    NSDictionary *interuptionDict = notification.userInfo;
    NSInteger routeChangeReason = [[interuptionDict valueForKey:AVAudioSessionRouteChangeReasonKey] integerValue];
    switch (routeChangeReason) {
        case AVAudioSessionRouteChangeReasonNewDeviceAvailable:
            NSLog(@"AVAudioSessionRouteChangeReasonNewDeviceAvailable");
            tipWithMessage(@"耳机插入");
            break;
        case AVAudioSessionRouteChangeReasonOldDeviceUnavailable:
            NSLog(@"AVAudioSessionRouteChangeReasonOldDeviceUnavailable");
            tipWithMessage(@"耳机拔出，停止播放操作");
            break;
        case AVAudioSessionRouteChangeReasonCategoryChange:
            // called at start - also when other audio wants to play
            tipWithMessage(@"AVAudioSessionRouteChangeReasonCategoryChange");
            break;
    }
}