如何在iOS 11.4上以编程方式更改卷 [英] How to change volume programmatically on iOS 11.4

问题描述

之前，我使用这种方法以编程方式设置音量：

Before, I was setting sound volume programmatically using this approach:

MPVolumeView *volumeView = [[MPVolumeView alloc] init];
UISlider *volumeViewSlider = nil;

for (UIView *view in [volumeView subviews])
{
    if ([view.class.description isEqualToString:@"MPVolumeSlider"])
    {
        volumeViewSlider = (UISlider *)view;
        break;
    }
}

[volumeViewSlider setValue:0.5 animated:YES];
[volumeViewSlider sendActionsForControlEvents:UIControlEventTouchUpInside];

直到iOS 11.4它运行良好（即使在iOS 11.3上），但在iOS 11.4上它没有'吨。体积值保持不变。有人可以帮忙解决这个问题吗？谢谢。

Till iOS 11.4 it was working well (even on iOS 11.3), but on iOS 11.4 it doesn't. Volume value remains unchanged. Can someone help with this issue? Thanks.

推荐答案

在一小段延迟解决问题后更改 volumeViewSlider.value 。

Changing volumeViewSlider.value after a small delay resolves problem.

- (IBAction)increase:(id)sender {
  MPVolumeView *volumeView = [[MPVolumeView alloc] init];
  UISlider *volumeViewSlider = nil;

  for (UIView *view in volumeView.subviews) {
    if ([view isKindOfClass:[UISlider class]]) {
      volumeViewSlider = (UISlider *)view;
      break;
    }
  }

  dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.01 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
    volumeViewSlider.value = 0.5f;
  });
}

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