ios - 为什么当我暂停 AVAudioPlayer 时锁屏音频控件会消失？

Question

我正在使用 AVAudioPlayer 的实例来播放音频文件。该应用程序配置为在后台播放音频，并设置了适当的 Audio Session 。我也成功接收了远程控制事件。

代码如下:

#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>

@interface ViewController ()

@property (nonatomic) AVAudioPlayer *player;

@end

@implementation ViewController

@synthesize player;

- (BOOL)canBecomeFirstResponder { return YES; }

- (void)viewDidLoad
{
    [super viewDidLoad];

    // Turn on remote control event delivery

    [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];

    // Set ourselves as the first responder

    [self becomeFirstResponder];

    // Set the audio session

    AVAudioSession *audioSession = [AVAudioSession sharedInstance];
    NSError *setCategoryError = nil;
    BOOL success = [audioSession setCategory:AVAudioSessionCategoryPlayback error:&setCategoryError];
    NSError *activationError = nil;
    success = [audioSession setActive:YES error:&activationError];

    // Play an mp3 with AVAudioPlayer

    NSString *audioFileName = @"%@/Via_Aurora.mp3";
    NSURL *audioURL = [NSURL fileURLWithPath:[NSString stringWithFormat:audioFileName, [[NSBundle mainBundle] resourcePath]]];
    player = [[AVPlayer alloc] initWithURL:audioURL];

    [player play];
}

- (void)viewWillDisappear:(BOOL)animated {

    // Turn off remote control event delivery & Resign as first responder

    [[UIApplication sharedApplication] endReceivingRemoteControlEvents];
    [self resignFirstResponder];

    // Don't forget to call super

    [super viewWillDisappear:animated];
}

- (void)remoteControlReceivedWithEvent:(UIEvent *)receivedEvent {

    if (receivedEvent.type == UIEventTypeRemoteControl) {

        switch (receivedEvent.subtype) {

            case UIEventSubtypeRemoteControlPreviousTrack:
                NSLog(@"prev");
                break;

            case UIEventSubtypeRemoteControlNextTrack:
                NSLog(@"next");
                break;

            case UIEventSubtypeRemoteControlPlay:
                [player play];
                break;

            case UIEventSubtypeRemoteControlPause:
                [player pause];
                break;

            default:
                break;
        }
    }
}

@end

当我运行应用程序时，音频会在 View 加载时播放。该应用程序在进入后台模式时会继续播放音频。我能够从控制中心(从应用程序或锁定屏幕访问)成功暂停和/或播放音频，但是，如果我访问锁定屏幕音频控件并暂停播放器，音乐会暂停并且锁定屏幕控件消失。我希望音乐会暂停，但控件不会消失。

在我使用的其他音频应用程序中，您可以暂停，然后从锁定屏幕播放音频。我忽略了什么吗？这是执行此类操作的正确方法吗？

Answer 1

你走在正确的轨道上......

您似乎缺少设置；

  MPNowPlayingInfoCenter nowPlayingInfo

没有它，你会得到描述的结果，IE按下暂停后，锁屏不再显示暂停，或者确实在播放歌曲。这是一个关于如何设置它的指南(我从我以前做过的工作代码中得到了这个，但我相信你能弄清楚是什么)。

    MPMediaItemArtwork *artwork = [[MPMediaItemArtwork alloc]initWithImage:albumImage];
    [MPNowPlayingInfoCenter defaultCenter].nowPlayingInfo = [NSDictionary dictionaryWithObjectsAndKeys:aSong.songTitle, MPMediaItemPropertyTitle,
                                                             aSong.artistName, MPMediaItemPropertyArtist, artwork, MPMediaItemPropertyArtwork,  1.0f, MPNowPlayingInfoPropertyPlaybackRate, nil];