如何知道iPhone相机是否准备好拍照?

问题描述：

在相机准备就绪之前调用[camera takePicture]时，它会显示以下消息:

When [camera takePicture] is called before the camera is ready, it spits out this message:

UIImagePickerController: ignoring request to take picture; camera is not yet ready.

我怎么知道什么时候可以拍照了?

How can I know when it is ready to take a photo?

[camera isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]始终返回true，即使它似乎还没有准备好.

[camera isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera] always returns true, even when it's apparently not ready.

答

正如@djromero所说的那样，可以使用AVFoundation解决方案(但不是代替的UIImagePickerController.您只需使用AVFoundation即可收到通知).

As @djromero said there is a solution by using AVFoundation (but not instead of UIImagePickerController. You just use AVFoundation to get a notification back).

[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(cameraIsReady:)
                                             name:AVCaptureSessionDidStartRunningNotification object:nil];

然后，一旦相机准备就绪，您会收到通知:

And then, once the camera is ready you got your notification:

- (void)cameraIsReady:(NSNotification *)notification
{   
    NSLog(@"Camera is ready...");
    // Whatever
}

我刚刚通过在UIImagePickerController演示文稿(我收到相机未准备好"消息)后调用takePicture并在通知回调内部调用它来进行测试，它像一种魅力一样工作.

I have just tested it by calling takePicture after UIImagePickerController presentation (where I got the 'camera is not ready' message) and right inside my notification callback, where it worked like a charm.

旁注:

[camera isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]始终返回Yes，因为它仅检查是否有可用的摄像头设备.实际上，Apple建议您在尝试初始化和呈现之前，必须始终检查它是否返回Yes并且您具有非nil委托(以提供通过标准接口通过dismiss选择器的方式).控制器.

[camera isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera] always returns Yes because it only checks that there is a camera device available. As a matter of fact, Apple recommends that you always must check that this returns Yes and that you have a non nil delegate (to provide a way to dismiss the picker through the standard interface) before you try to initialize and present the controller.

如何知道iPhone相机是否准备好拍照?

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