上篇讲了如何自定义一个UIView绘制出来一个方形的框。这篇分享如何使
AVFoundation来捕捉摄像头数据，并处理二维码解析出来的数据。
摄像头数据采集
摄像头采集很简单，只需要使用ios提供的API就能很容易的实现。在这个例子中，我们有一个初始化方法主要用来做摄像头数据采集的：
/**
初始化相机捕捉
**/
func initCapture(captureView:UIView, delegate:AVCaptureMetadataOutputObjectsDelegate)
{
let captureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
var error: NSError?
let input: AnyObject! = AVCaptureDeviceInput.deviceInputWithDevice(captureDevice, error: &error)
if (error != nil)
{
println("\(error?.localizedDescription)")
}
else
{
let captureViewFrame = captureView.frame
captureSession = AVCaptureSession()
captureSession?.addInput(input as! AVCaptureInput)
let captureMetadataOutput = AVCaptureMetadataOutput()
let screenHeight = captureViewFrame.height;
let screenWidth = captureViewFrame.width;
let cropRect = self.frame;
captureMetadataOutput.rectOfInterest = CGRectMake(cropRect.origin.y / screenHeight,cropRect.origin.x / screenWidth,cropRect.size.height / screenHeight,cropRect.size.width / screenWidth)
captureSession?.addOutput(captureMetadataOutput)
captureMetadataOutput.setMetadataObjectsDelegate(delegate, queue: dispatch_get_main_queue())
captureMetadataOutput.metadataObjectTypes = supportedBarCodes
videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
videoPreviewLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill
videoPreviewLayer?.frame = captureViewFrame
captureView.layer.addSublayer(videoPreviewLayer)
mMaskLayer = getMaskLayer(captureViewFrame)
captureView.layer.addSublayer(mMaskLayer)
captureView.bringSubviewToFront(self)
moveAllToFront(captureView)
}
}
这里这些API不光是适用于二维码，包括条形码等等都可以处理，主要是通过这个属性来过滤：
captureMetadataOutput.metadataObjectTypes = supportedBarCodes
这个属性可以有很多值：
[AVMetadataObjectTypeQRCode, AVMetadataObjectTypeCode128Code, AVMetadataObjectTypeCode39Code, AVMetadataObjectTypeCode93Code, AVMetadataObjectTypeUPCECode, AVMetadataObjectTypePDF417Code, AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypeAztecCode]
这里主要介绍二维码，所以我们只用一个。
这里还要对UIView的layer层级做一个说明。
我们使用了两个layer，一个是摄像头捕捉的layer：videoPreviewLayer
一个是蒙板layer这个layer的作用就是在中间扣一个白色的洞，让扫描框之外的区域看起来颜色更暗。初始化这个蒙板的代码如下：
/**
获取蒙板
**/
private func getMaskLayer(rect:CGRect) -> CAShapeLayer
{
let layer = CAShapeLayer.new()
layer.fillColor = mBackgroundColor.CGColor
layer.position = CGPoint(x: 0, y: 0)
let fillPath = UIBezierPath(rect: rect)
let scannerPath = UIBezierPath(rect: self.frame)
fillPath.appendPath(scannerPath)
layer.path = fillPath.CGPath
layer.fillRule = kCAFillRuleEvenOdd
return layer
}
有了这两个蒙板我们只要按照顺序添加layer到UIView就好了。这里要注意的一个地方就是到目前为止，我们如果直接在布局文件中，放入控件，比如底上的那行字，这个时候运行，你是看不到这行字的，原因就是这行字的层级比蒙板层级要低，所以被挡住了，所以我们在添加完蒙板后，我们把父控件的每一个子控件移动到最顶层，当然移动的时候要排除我们这个二维码View：
private func moveAllToFront(view:UIView)
{
for var i = 0; i < view.subviews.count; ++i
{
if let view: QRScannerView = view.subviews[i] as? QRScannerView
{
}
else
{
view.bringSubviewToFront(view.subviews[i] as! UIView)
}
}
}
到此摄像头捕捉部分就完成了，下面介绍怎么添加横线移动的动画。
添加扫描线动画
添加动画代码很简单直接贴了：
func startLineRunning()
{
let rect = self.bounds
let lineFrame = self.qrLine?.frame
print(lineFrame)
self.layer.removeAllAnimations()
UIView.animateWithDuration(1.5, animations: {
self.qrLine!.frame = CGRect(x: rect.origin.x, y: rect.height - lineFrame!.height, width: lineFrame!.width, height: lineFrame!.height)
}){(Bool) in
self.qrLine!.frame = CGRect(x: rect.origin.x, y: rect.origin.y, width: lineFrame!.width, height:lineFrame!.height)
if self.mIsEnableLineAnimation
{
self.startLineRunning()
}
}
}
完成动画后，我们需要在启动摄像头捕捉的时候让动画启动：
func startRunning()
{
captureSession?.startRunning()
self.mIsEnableLineAnimation = true
startLineRunning()
}
func stopRunning()
{
captureSession?.stopRunning()
self.mIsEnableLineAnimation = false
}
事例代码：
1、在controller实现协议：
AVCaptureMetadataOutputObjectsDelegate
2、其他代码包含启动、初始化、和摄像头捕捉的数据处理：
override func viewDidAppear(animated: Bool)
{
scanner.startRunning()
isCaputure = false
}
override func viewDidDisappear(animated: Bool)
{
scanner.stopRunning()
}
override func viewWillAppear(animated: Bool)
{
scanner.initCapture(self.view, delegate: self)
}
var isCaputure = false
/**
捕捉回调
**/
func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!)
{
var resultString = ""
if metadataObjects == nil || metadataObjects.count == 0
{
resultString = "scanner error"
}
else
{
let metadataObj = metadataObjects[0] as! AVMetadataMachineReadableCodeObject
if self.scanner.supportedBarCodes.filter({ $0 == metadataObj.type }).count > 0
{
let barCodeObject = self.scanner.videoPreviewLayer?.transformedMetadataObjectForMetadataObject(metadataObj as AVMetadataMachineReadableCodeObject) as! AVMetadataMachineReadableCodeObject
resultString = barCodeObject.stringValue
}
}
print("isCaputure \(isCaputure)")
if !isCaputure
{
isCaputure = true
self.requestValidate(resultString)
}
}
完整demo下载地址：DemoQRViewContinue reading
