Unity开发中如何实现iOS（iPhone）设备系统音量调节

首先明确iOS平台的规则限制：苹果没有开放直接修改系统全局音量的公开API，你在安卓端通过AudioManager.setStreamVolume直接修改音量的逻辑无法直接照搬，所有通过私有API强行修改系统音量的实现都会在App Store审核阶段被拒。

合规可过审的实现方案是使用苹果官方提供的MPVolumeView组件，最终实现的效果和你现有安卓代码完全一致：支持获取/设置0~1区间的媒体音量（对应安卓的STREAM_MUSIC流），调节时可弹出系统原生音量提示UI。

具体实现步骤 #

• 补全C#侧跨平台调用逻辑，通过条件编译区分安卓、iOS平台实现
• 编写iOS原生插件，封装MPVolumeView的音量读写逻辑，放到Unity指定的插件目录下

1. 补全后的C#跨平台音量控制代码 #

直接替换你原有的SmartphoneVolumeController类即可，原有安卓逻辑完全保留，新增iOS平台调用逻辑：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
#if UNITY_IOS
using System.Runtime.InteropServices;
#endif

public class SmartphoneVolumeController : MonoBehaviour
{
    public static SmartphoneVolumeController Instance;
    private AndroidNativeVolumeService androidService;

    private void Awake()
    {
        if (Instance == null) Instance = this;
        else Destroy(gameObject);
    }

#if UNITY_IOS
    [DllImport("__Internal")]
    private static extern float iOS_GetSystemVolume();
    [DllImport("__Internal")]
    private static extern void iOS_SetSystemVolume(float volume);
#endif

    /// <summary>
    /// 获取当前系统媒体音量，返回值范围0~1
    /// </summary>
    public float GetSystemVolume()
    {
#if UNITY_ANDROID
        if (androidService == null) androidService = new AndroidNativeVolumeService();
        return androidService.GetSystemVolume();
#elif UNITY_IOS
        return iOS_GetSystemVolume();
#else
        return 1f;
#endif
    }

    /// <summary>
    /// 设置系统媒体音量，传入值范围0~1
    /// </summary>
    public void SetSystemVolume(float volumeValue)
    {
        volumeValue = Mathf.Clamp01(volumeValue);
#if UNITY_ANDROID
        if (androidService == null) androidService = new AndroidNativeVolumeService();
        androidService.SetSystemVolume(volumeValue);
#elif UNITY_IOS
        iOS_SetSystemVolume(volumeValue);
#endif
    }

    // 原有安卓音量服务实现保持不变
    public class AndroidNativeVolumeService
    {
        static int STREAMMUSIC;
        static int FLAGSHOWUI = 1;
        private static AndroidJavaObject audioManager;
        private static AndroidJavaObject deviceAudio
        {
            get
            {
                if (audioManager == null)
                {
                    AndroidJavaClass unityPlayerClass = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
                    AndroidJavaObject currentActivity = unityPlayerClass.GetStatic<AndroidJavaObject>("currentActivity");
                    AndroidJavaObject context = currentActivity.Call<AndroidJavaObject>("getApplicationContext");
                    AndroidJavaClass audioManagerClass = new AndroidJavaClass("android.media.AudioManager");
                    AndroidJavaClass contextClass = new AndroidJavaClass("android.content.Context");
                    STREAMMUSIC = audioManagerClass.GetStatic<int>("STREAM_MUSIC");
                    string Context_AUDIO_SERVICE = contextClass.GetStatic<string>("AUDIO_SERVICE");
                    audioManager = context.Call<AndroidJavaObject>("getSystemService", Context_AUDIO_SERVICE);
                    if (audioManager != null)
                        Debug.Log("[AndroidNativeVolumeService] Android Audio Manager successfully set up");
                    else
                        Debug.Log("[AndroidNativeVolumeService] Could not read Audio Manager");
                }
                return audioManager;
            }
        }
        private static int GetDeviceMaxVolume()
        {
            return deviceAudio.Call<int>("getStreamMaxVolume", STREAMMUSIC);
        }
        public float GetSystemVolume()
        {
            int deviceVolume = deviceAudio.Call<int>("getStreamVolume", STREAMMUSIC);
            float scaledVolume = (float)(deviceVolume / (float)GetDeviceMaxVolume());
            return scaledVolume;
        }
        public void SetSystemVolume(float volumeValue)
        {
            int scaledVolume = (int)(volumeValue * (float)GetDeviceMaxVolume());
            deviceAudio.Call("setStreamVolume", STREAMMUSIC, scaledVolume, FLAGSHOWUI);
        }
    }
}

2. iOS原生插件代码 #

新建名为iOSVolumeController.mm的文件，放到Unity项目的Assets/Plugins/iOS目录下，代码内容如下：

#import <Foundation/Foundation.h>
#import <MediaPlayer/MediaPlayer.h>
#import <AVFoundation/AVFoundation.h>
#import <UIKit/UIKit.h>

static MPVolumeView *volumeView = nil;
static UISlider *volumeSlider = nil;

void SetupVolumeView()
{
    if (volumeView != nil) return;
    // 初始化音频会话，保证音量控制在应用前后台都正常生效
    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:nil];
    [[AVAudioSession sharedInstance] setActive:YES error:nil];
    
    // 若不需要显示系统音量弹窗，将frame改为CGRectMake(-100, -100, 10, 10)放到屏幕外即可
    volumeView = [[MPVolumeView alloc] initWithFrame:CGRectMake(0, [UIScreen mainScreen].bounds.size.height - 10, [UIScreen mainScreen].bounds.size.width, 10)];
    volumeView.showsVolumeSlider = YES;
    [[[UIApplication sharedApplication] keyWindow] addSubview:volumeView];
    
    // 查找MPVolumeView内置的音量滑块控件
    for (UIView *view in volumeView.subviews) {
        if ([view isKindOfClass:[UISlider class]]) {
            volumeSlider = (UISlider *)view;
            break;
        }
    }
}

extern "C" float iOS_GetSystemVolume()
{
    SetupVolumeView();
    if (volumeSlider == nil) return 1.0f;
    return volumeSlider.value;
}

extern "C" void iOS_SetSystemVolume(float volume)
{
    SetupVolumeView();
    if (volumeSlider == nil) return;
    volume = fmaxf(0.0f, fminf(1.0f, volume));
    [volumeSlider setValue:volume animated:NO];
    // 触发滑块值变更事件，生效系统音量修改
    [volumeSlider sendActionsForControlEvents:UIControlEventTouchUpInside];
}

注意事项 #

• 该方案使用苹果官方公开API实现，不会触发App Store审核拒审，接口返回/传入的音量值和安卓端保持一致，都是0~1的浮点数，上层调用不需要做额外适配
• 不要尝试直接修改AVAudioSession的outputVolume属性，该属性为只读，强行调用私有API修改会直接被审核打回
• 打包Xcode工程时，Unity会自动引入MediaPlayer、AVFoundation、UIKit等依赖框架，不需要手动在Xcode中额外配置
• 若应用切换场景后音量滑块失效，可在场景加载完成后重新调用一次SetupVolumeView逻辑（也可将MPVolumeView实例绑定到不销毁的根节点上保证全局存活）

内容的提问来源于stack exchange，提问作者sayt