Draw overlay on camera iOS

问题

Users need to be able to take photo of their ID. I need to add a blue frame to camera view as a guide. Guide should have same aspect ratio on all device sizes and fit a label with instructions. Can I accomplish this using UIImagePicker?

Here is some incomplete code. Thanks for any help.

UIImageView *overlayImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@""]];
CGRect overlayRect = CGRectMake(0, 0, self.view.frame.size.height - 16, self.view.frame.size.width - 16);
[overlayImage setFrame:overlayRect];
[self.imagePicker setCameraOverlayView:overlayImage];

回答1:

Use AVCaptureDevice, AVCaptureSession, AVCaptureVideoPreviewLayer and AVCapturePhotoOutput.

Set AVCaptureDeviceInput as input of capture session, and photo output as output of capture session. Initialize AVCaptureVideoPreviewLayer with AVCaptureSession and add to your view.layer thought addSublayer. You can use UIViewController from storyboard or programmatically instantiated controller, add picture of overlay or cornered view.layer.borderWidth or UIBezierPath. Set up controller as AVCapturePhotoCaptureDelegate, add delegate methods. Use capturePhoto(with:delegate:) method. Enjoy.

来源：https://stackoverflow.com/questions/53180657/draw-overlay-on-camera-ios