目前在 Objective-C 中，我使用 Zbar(http://zbar.sourceforge.net/) 来生成和读取 QR 码。现在，我只想继续 Swift 开发，是否有任何关于在 Swift 中生成和读取 QR 码的“方法”或库？
【问题讨论】：
标签： swift
这是我为快速生成二维码而编写的代码。
//MARK:- generate QR code
func generateQRImage(stringQR:NSString, withSizeRate rate:CGFloat) -> UIImage
{
var filter:CIFilter = CIFilter(name:"CIQRCodeGenerator")
filter.setDefaults()
var data:NSData = stringQR.dataUsingEncoding(NSUTF8StringEncoding)!
filter.setValue(data, forKey: "inputMessage")
var outputImg:CIImage = filter.outputImage
var context:CIContext = CIContext(options: nil)
var cgimg:CGImageRef = context.createCGImage(outputImg, fromRect: outputImg.extent())
var img:UIImage = UIImage(CGImage: cgimg, scale: 1.0, orientation: UIImageOrientation.Up)!
var width = img.size.width * rate
var height = img.size.height * rate
UIGraphicsBeginImageContext(CGSizeMake(width, height))
var cgContxt:CGContextRef = UIGraphicsGetCurrentContext()
CGContextSetInterpolationQuality(cgContxt, kCGInterpolationNone)
img.drawInRect(CGRectMake(0, 0, width, height))
img = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return img
}
【讨论】：
从 iOS 7 开始，iOS 设备可以读取二维码。但是，没有生成 QR 码的内置方法。这是一个又快又脏的二维码阅读器。
首先，import AVFoundation 并添加 AVCaptureMetadataOutputObjectsDelegate
接下来，设置捕获会话：
func captureQRCode() {
let session = AVCaptureSession()
let device = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
let input = AVCaptureDeviceInput.deviceInputWithDevice(device, error: nil) as AVCaptureDeviceInput
session.addInput(input)
let output = AVCaptureMetadataOutput()
output.setMetadataObjectsDelegate(self, queue: dispatch_get_main_queue())
session.addOutput(output)
output.metadataObjectTypes = [AVMetadataObjectTypeQRCode]
let previewLayer = AVCaptureVideoPreviewLayer(session: session)
let bounds = self.view.layer.bounds
previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
previewLayer.bounds = bounds
previewLayer.position = CGPointMake(CGRectGetMidX(bounds), CGRectGetMidY(bounds))
self.view.layer.addSublayer(previewLayer)
session.startRunning()
}
最后，处理委托
func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!) {
for item in metadataObjects {
if let metadataObject = item as? AVMetadataMachineReadableCodeObject {
if metadataObject.type == AVMetadataObjectTypeQRCode {
println("QR Code: \(metadataObject.stringValue)")
}
}
}
}
【讨论】：
这个 GitHub 项目提供了一些关于如何生成二维码的代码：
https://github.com/aschuch/QRCode
// NSData
let data = "http://schuch.me".dataUsingEncoding(NSISOLatin1StringEncoding)
let qrCode = QRCode(data)
qrCode.image
至于阅读，这里还有一个不错的GitHub项目：
https://github.com/yannickl/QRCodeReader.swift
// Good practice: create the reader lazily to avoid cpu overload during the
// initialization and each time we need to scan a QRCode
lazy var reader = QRCodeReaderViewController(metadataObjectTypes: [AVMetadataObjectTypeQRCode])
@IBAction func scanAction(sender: AnyObject) {
// Retrieve the QRCode content
// By using the delegate pattern
reader.delegate = self
// Or by using the closure pattern
reader.completionBlock = { (result: String?) in
println(result)
}
// Presents the reader as modal form sheet
reader.modalPresentationStyle = .FormSheet
presentViewController(reader, animated: true, completion: nil)
}
// MARK: - QRCodeReader Delegate Methods
func reader(reader: QRCodeReader, didScanResult result: String) {
self.dismissViewControllerAnimated(true, completion: nil)
}
func readerDidCancel(reader: QRCodeReader) {
self.dismissViewControllerAnimated(true, completion: nil)
}
我建议您查看这两个项目并结合代码来实现您想要的行为。
【讨论】：
这是我编写的用于在 Objective-C 中生成二维码的代码：
#pragma mark - qrimage
-(UIImage *)generateQRimg:(NSString *)a withsize:(CGFloat)b
{
CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
[filter setDefaults];
NSData *data = [a dataUsingEncoding:NSUTF8StringEncoding];
[filter setValue:data forKey:@"inputMessage"];
CIImage *outputImage = [filter outputImage];
CIContext *context = [CIContext contextWithOptions:nil];
CGImageRef cgImage = [context createCGImage:outputImage
fromRect:[outputImage extent]];
UIImage *image = [UIImage imageWithCGImage:cgImage
scale:1.
orientation:UIImageOrientationUp];
// Resize without interpolating
UIImage *resized = [self resizeImage:image
withQuality:kCGInterpolationNone
rate:b];
CGImageRelease(cgImage);
return resized;
}
- (UIImage *)resizeImage:(UIImage *)image withQuality (CGInterpolationQuality)quality rate:(CGFloat)rate
{
UIImage *resized = nil;
CGFloat width = image.size.width * rate;
CGFloat height = image.size.height * rate;
UIGraphicsBeginImageContext(CGSizeMake(width, height));
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetInterpolationQuality(context, quality);
[image drawInRect:CGRectMake(0, 0, width, height)];
resized = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return resized;
}
【讨论】：
Swift 中的二维码生成器：
在viewDidLoad：
var qrcodeImage: CIImage!
@IBOutlet var qrtext: UITextField!
@IBOutlet var imgQRCode: UIImageView!
@IBAction func displayQRcode(sender: AnyObject) {
if qrcodeImage == nil {
if qrtext.text == "" {
return
}
let data = qrtext.text!.dataUsingEncoding(NSISOLatin1StringEncoding, allowLossyConversion: false)
let filter = CIFilter(name: "CIQRCodeGenerator")
filter!.setValue(data, forKey: "inputMessage")
filter!.setValue("Q", forKey: "inputCorrectionLevel")
qrcodeImage = filter!.outputImage
qrtext.resignFirstResponder()
displayQRCodeImage()
}
else {
self.imgQRCode.image = nil
self.qrcodeImage = nil
}
}
func displayQRCodeImage() {
let scaleX = imgQRCode.frame.size.width / qrcodeImage.extent.size.width
let scaleY = imgQRCode.frame.size.height / qrcodeImage.extent.size.height
let transformedImage = qrcodeImage.imageByApplyingTransform(CGAffineTransformMakeScale(scaleX, scaleY))
imgQRCode.image = UIImage(CIImage: transformedImage)
}
对于二维码阅读器
【讨论】：
SWIFT 3： 二维码阅读器
第一步： 只需在 info.plist 中添加一行，然后在新创建的行中输入 Privacy - CameraUsageDescription 并添加一个字符串表示用于告知用户为什么需要在您的应用中访问相机。
第二步：在您的 ViewController 类中使用此代码
class QrCodeScannerViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
var calssName:String = "QrCodeScannerViewController"
var captureSession:AVCaptureSession?
var videoPreviewLayer:AVCaptureVideoPreviewLayer?
var qrCodeFrameView:UIView?
@IBOutlet weak var messageLabel: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
captureQRCode()
}
/* Open camera to capture QR CODE */
func captureQRCode() {
captureSession = AVCaptureSession()
let device = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)
let input = try! AVCaptureDeviceInput(device: device) as AVCaptureDeviceInput
captureSession?.addInput(input)
let output = AVCaptureMetadataOutput()
output.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
captureSession?.addOutput(output)
output.metadataObjectTypes = [AVMetadataObjectTypeQRCode]
videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
let bounds = self.view.layer.bounds
videoPreviewLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill
videoPreviewLayer?.bounds = bounds
videoPreviewLayer?.position = CGPoint(x:bounds.midX, y:bounds.midY)
self.view.layer.addSublayer(videoPreviewLayer!)
captureSession?.startRunning()
}
/* onAtivityResult from App Delegate */
func captureOutput(_ captureOutput: AVCaptureOutput!,
didOutputMetadataObjects metadataObjects: [Any]!,
from connection: AVCaptureConnection!) {
for item in metadataObjects {
if let metadataObject = item as? AVMetadataMachineReadableCodeObject {
if metadataObject.type == AVMetadataObjectTypeQRCode {
print("QR Code: \(metadataObject.stringValue)")
hideCamera(voucherHashkey: metadataObject.stringValue)
}
}
}
}
/* Hide camera after getting result */
func hideCamera(voucherHashkey:String){
self.captureSession?.stopRunning()
self.videoPreviewLayer?.removeFromSuperlayer()
self.videoPreviewLayer = nil;
self.captureSession = nil;
// sendVocherDataToServer(voucherHashKey: voucherHashkey)
}
}
【讨论】：
考虑到AVCaptureSession 的startRunning() 是阻塞调用和其他详细信息，可以在此处找到二维码阅读器的不太快速和肮脏的 Swift 实现：
https://bitbucket.org/snippets/stefanpilger/gE98R/qr-code-reader-class-swift
【讨论】：