详解：IOS二维码的生成与扫描过程

 // 二维码的生成 // 1、创建过滤器 CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"]; // 2、恢复滤镜的默认属性 [filter setDefaults]; // 3、设置内容 NSString *str = @"这是一个二维码的生成结果"; NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding]; // 使用KVO设置属性 [filter setValue:data forKey:@"inputMessage"]; // 4、获取输出文件 CIImage *outputImage = [filter outputImage]; // 5、显示二维码 self.imageView.image = [UIImage imageWithCIImage:outputImage];

/** * 根据CIImage生成指定大小的UIImage * * @param image CIImage * @param size 图片宽度 */- (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size{ CGRect extent = CGRectIntegral(image.extent); CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent)); // 1.创建bitmap; size_t width = CGRectGetWidth(extent) * scale; size_t height = CGRectGetHeight(extent) * scale; CGColorSpaceRef cs = CGColorSpaceCreateDeviceGray(); CGContextRef bitmapRef = CGBitmapContextCreate(nil, width, height, 8, 0, cs, (CGBitmapInfo)kCGImageAlphaNone); CIContext *context = [CIContext contextWithOptions:nil]; CGImageRef bitmapImage = [context createCGImage:image fromRect:extent]; CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone); CGContextScaleCTM(bitmapRef, scale, scale); CGContextDrawImage(bitmapRef, extent, bitmapImage); // 2.保存bitmap到图片 CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef); CGContextRelease(bitmapRef); CGImageRelease(bitmapImage); return [UIImage imageWithCGImage:scaledImage];}

NSString *str = @http://www.baidu.com;

#import "ViewController.h"#import @interface ViewController () /**显示图层*/@property (nonatomic, strong) AVCaptureVideoPreviewLayer *layer;/**捕捉会话*/@property (nonatomic, strong) AVCaptureSession *session;@end@implementation ViewController- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{ // 二维码的扫描 // 1、创建捕捉会话 AVCaptureSession *session = [[AVCaptureSession alloc] init]; self.session = session; // 2.添加输入设备(数据从摄像头输入) AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo]; AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil]; [session addInput:input]; // 3、添加输出数据(示例对象-->类对象-->元类对象-->根元类对象) AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init]; [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()]; [session addOutput:output]; // 3.1.设置输入元数据的类型(类型是二维码数据) [output setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]]; // 4、添加扫描图层 AVCaptureVideoPreviewLayer *layer = [AVCaptureVideoPreviewLayer layerWithSession:session]; layer.frame = self.view.bounds; [self.view.layer addSublayer:layer]; self.layer = layer; // 5、开始扫描 [session startRunning];}/** * 实现output的回调方法 */- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{ // 数组metadataObjects中存放结果数据 if (metadataObjects.count > 0) { // 获取最终的读取结果 AVMetadataMachineReadableCodeObject *object = [metadataObjects lastObject]; NSLog(@"%@",object.stringValue); [self.session stopRunning]; [self.layer removeFromSuperlayer]; } else { NSLog(@"没有扫描到数据"); }}