在AVCaptureDevice上切换Flash需要停止和启动AVCaptureSEssion [英] Toggling Flash on AVCaptureDevice requires Stopping and Starting AVCaptureSEssion

问题描述

在iOS 7中，为 AVCaptureDevice 使用时更改闪光灯状态：

In iOS 7 when changing the flash state for AVCaptureDevice using:

if ([self.avCaptureDevice isFlashModeSupported:self.avCaptureFlashMode])
{
    NSError *error = nil;
    [self.avCaptureDevice lockForConfiguration:&error];
    if (!error) [self.avCaptureDevice setFlashMode:self.avCaptureFlashMode];
    [self.avCaptureDevice unlockForConfiguration];
}

设备不会使用闪存，除非 AVCaptureSessions 停止并以以下方式启动：

The device won't use the flash unless the AVCaptureSessions is stopped and started with:

[self.avCaptureSession stopRunning];
[self.avCaptureSession startRunning];

这会使相机短暂闪烁为黑色。

This causes the camera to flash to black briefly. Is it possible to toggle the flash without stopping/starting the session?

推荐答案

我在iOS7中有一个类似的Flash相关的问题，其中仍然如果会话具有多个输出（静态和视频数据）并使用闪存，捕获将失败。在 https://devforums.apple.com/message/894764 中找到了解决方法（删除第二个在调用 captureStillImageAsynchronouslyFromConnection：completion 之前输出）。显然，这也会暂停视频，但它可能更适合，如果你有一个快门动画反正。

I had a similar flash related problem in iOS7 where still capture would fail if the session had multiple outputs (still and videodata) and the flash was used. Found a workaround in https://devforums.apple.com/message/894764 (removing the second output before calling captureStillImageAsynchronouslyFromConnection:completion). Obviously this will also pause the video, but it may be more suitable if you have a shutter animation anyway.

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