CoreImage框架二维码实例

生成二维码过程：

实例化二维码滤镜

恢复滤镜的默认属性
将字符串转化为NSData
通过KVC设置滤镜inputMessage数据
获得滤镜输出的图像
将CIImage转化成为UIImage，并放大显示
通过位图创建高清图片

实现：

主要通过iOS提供的CIFilter滤镜技术（内部支持二维码）

以下方法作为NSString的分类的一个方法实现（返回值就是二维码图片）


-(UIImage *)createQRCodeErrorCorrectionLevel:(ErrorCorrectionLevel)errorCorrectionLevel{

//实例化二维码滤镜  CIQRCodeGenerator  二维码生成器滤镜

CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];

[filter setDefaults]; //设置滤镜默认属性

//将NSString转换成NSData

NSData *data = [self dataUsingEncoding:NSUTF8StringEncoding];

//KVC设置滤镜inputMessage数据

[filter setValue:data forKey:@"inputMessage"];

[filter setValue:[self convertErrorCorrectionLevelToString:errorCorrectionLevel] forKey:@"inputCorrectionLevel"];

// 滤镜输出的图片CIImage

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];

//放大处理

UIImage *resizedImage = [self resizeImage:image

withQuality:kCGInterpolationNone

rate:10.0];

return resizedImage;

}

自定义图片放大缩小方法


- (UIImage *)resizeImage:(UIImage *)image

withQuality:(CGInterpolationQuality)quality

rate:(CGFloat)rate {

UIImage *resizedImg = 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)];

resizedImg = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return resizedImg;

}

生成自定义的二维码：（二维码是有上下方位的，三角定位）

纠错率：有些二维码中间有个图片还能被识别，那是因为二维码的纠错率，可以根据设置纠正不同比例的错误

通过KVC设置滤镜的纠错率， [filter setValue:@“M” forKey:@“inputCorrectionLevel” ];

L：表示7%的字码被修正 M:15% Q: 25% H:30%

中间加个图片什么的，另外设置纠错率就可以了

识别二维码：二维码探测器

1、实例化二维码探测器


CIDetector *detector = [CIDetector detectorOfType:CIDetectorTypeQRCode context:nil options:@{CIDetectorAccuracy:CIDetectorAccuracyHigh}];

UIImage *img = [UIImage imageNamed:@""];

2、识别二维码, 可识别一张图中多个二维码的情况


NSArray *feartureArr = [detector featuresInImage:img.CIImage];

for (CIQRCodeFeature *feature in feartureArr) {

NSLog(@"二维码内容---%@",feature.messageString);

NSLog(@"二维码bounds---%@",NSStringFromCGRect(feature.bounds));

}

扫描二维码

实例化拍摄设备

设置输入设备
设置元数据输出处理对象
添加拍摄会话
视频预览图层
启动会话
监听元数据处理后的结果


//获取设备摄像头

_device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

if([_device isFocusModeSupported:AVCaptureFocusModeContinuousAutoFocus]

{

_device.focusMode = AVCaptureFocusModeContinuousAutoFocus;

}

if([_device isFocusModeSupported:AVCaptureFocusModeLocked]) {

[_device unlockForConfiguration];

}

//设置输入设备

_input = [AVCaptureDeviceInput deviceInputWithDevice:_device error:nil];

//设置元数据输出处理对象

_output = [[AVCaptureMetadataOutput alloc]init];

[_output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];

//添加拍摄会话

_session = [[AVCaptureSession alloc]init];

[_session setSessionPreset:AVCaptureSessionPresetHigh];

//设置会话输入输出对象

if ([_session canAddInput:_input]) {

[_session addInput:_input];

}

if ([_session canAddOutput:_output]) {

[_session addOutput:_output];

}

// 条码类型 AVMetadataObjectTypeQRCode

if ([_output.availableMetadataObjectTypes containsObject:AVMetadataObjectTypeQRCode]) {//做一些空值处理，容易导致崩溃

_output.metadataObjectTypes =@[AVMetadataObjectTypeQRCode];

}

else {

_alerView = [[UIAlertView alloc]initWithTitle:@"请在iPhone的\"设置-隐私-相机\"选项中，允许微信访问你的相机."

message:nil

delegate:self

cancelButtonTitle:@"残忍拒绝"

otherButtonTitles:@"去设置", nil];

[_alerView show];

}

//视频预览图层

_preview =[AVCaptureVideoPreviewLayer layerWithSession:_session];

_preview.videoGravity = AVLayerVideoGravityResizeAspectFill;

_preview.frame =CGRectMake(0,0,kScreenWidth,kScreenHeight);

[self.view.layer insertSublayer:_preview atIndex:0];

//启动会话

[_session startRunning];

//放大相机

[self setVideoZoomFactor:1.5];

放大相机


- (void)setVideoZoomFactor:(CGFloat)zoomFactor{

if (!_device) {

return;

}

_initialPinchZoom = _device.videoZoomFactor;

NSError* error = nil;

[_device lockForConfiguration:&error];

if (!error) {

if (_device.activeFormat.videoMaxZoomFactor > 1.5) {

_device.videoZoomFactor = zoomFactor;

}

[_device unlockForConfiguration];

}

}

设备扫描输出代理

AVCaptureMetadataOutputObjectsDelegate


- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects

fromConnection:(AVCaptureConnection *)connection {

NSString *qrcodeResult;

if (!metadataObjects) {

return;

}

if ([metadataObjects count] > 0 ) {

AVMetadataMachineReadableCodeObject * metadataObject = [metadataObjects objectAtIndex:0];

qrcodeResult = [NSString stringWithFormat:@"%@",metadataObject.stringValue];

}

if (!qrcodeResult){

return;

}

}

CoreImage框架 二维码实例