Preface
During development, you often encounter QR codes and barcodes, but there’s always a tricky problem: how do you make the scanning frame follow the detected QR code (i.e., intelligently detect the scanned layer.bounds)?
There’s an article that describes the development process, so I won’t repeat it here. If anyone needs me to translate it, please leave a comment at the bottom and I’ll update the code promptly.
Building a Barcode and QR Code Reader in Swift 3 and Xcode 8
The core code is as follows, using the AVCaptureMetadataOutputObjectsDelegate delegate:
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func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {
// Check if the metadataObjects array is not nil and it contains at least one object.
if metadataObjects == nil || metadataObjects.count == 0 {
qrCodeFrameView?.frame = CGRect.zero
messageLabel.text = "No QR code is detected"
return
}
// Get the metadata object.
let metadataObj = metadataObjects[0] as! AVMetadataMachineReadableCodeObject
if metadataObj.type == AVMetadataObjectTypeQRCode {
// If the found metadata is equal to the QR code metadata then update the status label's text and set the bounds
let barCodeObject = videoPreviewLayer?.transformedMetadataObject(for: metadataObj)
// Core code here
qrCodeFrameView?.frame = barCodeObject!.bounds
if metadataObj.stringValue != nil {
messageLabel.text = metadataObj.stringValue
}
}
}}
qrCodeFrameView?.frame = barCodeObject!.bounds This is the core line — just get barCodeObject.bounds and assign it to the transparent view we created. Final Project
End of article