How to set scanning bound using AVFoundation

问题

I am trying barcode scanner in one of my iOS application. I had successfully implemented the barcode scanner.

But currently barcode scanning is displayed in full screen only. But what I want is that, the video should be viewed in full screen and the barcode should be scanned in particular portion only. That is, if the barcode is placed in that portion then only it should be displayed. Below is my current code:

session=[[AVCaptureSession alloc]init];
device=[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
NSError *error=nil;

input=[AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
if (input) {
    [session addInput:input];
}
else{
    NSLog(@"Errod : %@",error);
}

output=[[AVCaptureMetadataOutput alloc]init];
[output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
[session addOutput:output];

output.metadataObjectTypes=[output availableMetadataObjectTypes];

prevLayer=[AVCaptureVideoPreviewLayer layerWithSession:session];
[prevLayer setFrame:self.view.bounds];
[prevLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
[self.view.layer addSublayer:prevLayer];

[session startRunning];

[self.view bringSubviewToFront:self.lblCode];
[self.view bringSubviewToFront:self.imgShade1];
[self.view bringSubviewToFront:self.imgShade2];

回答1:

This is what you are after:

CGRect visibleMetadataOutputRect = [prevLayer metadataOutputRectOfInterestForRect:areaOfInterest];

output.rectOfInterest = visibleMetadataOutputRect;

where areaOfInterest is a CGRect. Hope this solves the issue.

回答2:

Maybe it's late to answer this question, but I've just overcome this issue myself. So, hope to help others later.

The keyword is rectOfInterest of AVCaptureMetadataOutput, and here's how I set mine.

CGSize size = self.view.bounds.size;
_output.rectOfInterest = CGRectMake(cropRect.origin.y/size.height, cropRect.origin.x/size.width, cropRect.size.height/size.height, cropRect.size.width/size.width);

For more detail, you can check Document from Apple Inc.

Good Luck. :)

来源：https://stackoverflow.com/questions/23284762/how-to-set-scanning-bound-using-avfoundation