将音量弹出框替换为更细微的方式，以便在用户使用音量键更改音量时显示音量。

原因和方法

当用户点击音量键时出现的 iOS 默认音量状态弹出框是一个巨大且突兀的光面视图，会遮盖显示的内容。此库提供了一种显示更细微指示器的方式。为确保不显示弹出框，需要满足两个条件

需要激活一个 AVAudioSession
一个 MPVolumeView 需要位于当前视图的层级结构中，并且其 alpha 值需要大于 0

将 SubtleVolume 添加到视图后，会自动启动一个音频会话，并将视图的 alpha 值在隐藏状态下设置为 0.0001。

开始使用

使用其便捷初始化器之一创建 SubtleVolume 的实例，并设置其位置（您可以设置框架或让自动布局处理）

let volume = SubtleVolume(style: .plain)
volume.frame = CGRect(x: 0, y: 10, width: UIScreen.main.bounds.width, height: 4) // or wherever you like

设置 barTintColor 属性

volume.barTintColor = .red

如果需要，设置动画类型（不使用动画将导致指示器始终可见）

volume.animation = .slideDown

将视图添加到您的层级结构中

view.addSubview(volume)

要以编程方式更改音量

try? volume.setVolumeLevel(0.5)

或者使用便捷方法

try? volume.decreaseVolume(by: 0.2, animated: true)
try? volume.increaseVolume(by: 0.2, animated: true)

辅助图像

您可以提供一个辅助图像，该图像将显示在栏的左侧。请参阅委托方法

func subtleVolume(_ subtleVolume: SubtleVolume, accessoryFor value: Double) -> UIImage? {
  return value > 0 ? #imageLiteral(resourceName: "volume-on.pdf") : #imageLiteral(resourceName: "volume-off.pdf")
}

iPhone X(S/R) 支持

想要更花哨地在刘海区域显示音量条吗？查看演示项目。主要思路如下

class ViewController: UIViewController {
  let volume = SubtleVolume(style: .rounded)
  var statusBarVisible = true

  // ...

  override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

    if view.safeAreaInsets.top > 0 {
      volume.padding = CGSize(width: 2, height: 8)
      volume.frame = CGRect(x: 16, y: 8, width: 60, height: 20)
    } else {
      // older phones here
    }
  }

  override var preferredStatusBarStyle: UIStatusBarStyle {
    return .lightContent
  }

  override var preferredStatusBarUpdateAnimation: UIStatusBarAnimation {
    return .slide
  }

  override var prefersStatusBarHidden: Bool {
    return !statusBarVisible
  }
}

extension ViewController: SubtleVolumeDelegate {
  func subtleVolume(_ subtleVolume: SubtleVolume, didChange value: Double) {
    if !subtleVolume.isAnimating && view.safeAreaInsets.top > 0 {
      statusBarVisible = true
      UIView.animate(withDuration: 0.1) {
        self.setNeedsStatusBarAppearanceUpdate()
      }
    }
  }

  func subtleVolume(_ subtleVolume: SubtleVolume, willChange value: Double) {
    if !subtleVolume.isAnimating && view.safeAreaInsets.top > 0 {
      statusBarVisible = false
      UIView.animate(withDuration: 0.1) {
        self.setNeedsStatusBarAppearanceUpdate()
      }
    }
  }
}

处理后台状态

一旦您的应用程序进入后台，您需要在它变为活动状态时恢复会话

NotificationCenter.default.addObserver(volume, selector: #selector(SubtleVolume.resume), name: NSNotification.Name.UIApplicationDidBecomeActive, object: nil)

SubtleVolume 会在 deinit 时自动删除观察者。

雇佣我们

由 Andrea Mazzini 编写。我们提供自由职业工作，请随时在此处联系我们。

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MIT 许可证

Copyright (c) 2017-2018 Andrea Mazzini. All rights reserved.

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copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
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permit persons to whom the Software is furnished to do so, subject to
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