AVCaptureMetadataOutputObjectsDelegate not called in swift 4 for QR scanner

问题

I was working on QR code scanner app on iOS where i was getting output AVCaptureOutput on the delegate method captureOutput:didOutputMetadataObjects:fromConnection:.

It was working perfectly on swift 3. After I've updated to xcode 9 and swift 4, it stopped working.

回答1:

Okay I've found an update here.

Found that AVCaptureMetadataOutputObjectsDelegate method is changed

from

captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!)

metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection)

After changing this delegate method, its working good now.

回答2:

in Swift 4:

Replace

let metadataOutput = AVCaptureMetadataOutput()
metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
metadataOutput.metadataObjectTypes = metadataOutput.availableMetadataObjectTypes

With:

let metadataOutput = AVCaptureMetadataOutput()
metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
let supportedCodeTypes = [AVMetadataObject.ObjectType.upce,
                          AVMetadataObject.ObjectType.code39,
                          AVMetadataObject.ObjectType.code39Mod43,
                          AVMetadataObject.ObjectType.code93,
                          AVMetadataObject.ObjectType.code128,
                          AVMetadataObject.ObjectType.ean8,
                          AVMetadataObject.ObjectType.ean13,
                          AVMetadataObject.ObjectType.aztec,
                          AVMetadataObject.ObjectType.pdf417,
                          AVMetadataObject.ObjectType.qr]

metadataOutput.metadataObjectTypes = supportedCodeTypes

来源：https://stackoverflow.com/questions/46639519/avcapturemetadataoutputobjectsdelegate-not-called-in-swift-4-for-qr-scanner

标签

qr-code

ios11

swift4