二维码的生成与扫描

生成二维码

1. 导入库#import <CoreImage/CoreImage.h>

2. 通过滤镜CIFilter生成二维码

- (UIImage *)createQRCode:(NSString *)code{
    //1. 创建过滤器, 这里的@"CIQRCodeGenerator"是固定的
    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    //2.恢复默认设置
    [filter setDefaults];
    //3. 给过滤器添加数据
    NSData *codeData = [code dataUsingEncoding:NSUTF8StringEncoding];
    //4. 数据value必须是NSData类型的
    [filter setValue:codeData forKey:@"inputMessage"];
    //5. 生成二维码
    CIImage *ciImg = filter.outputImage;
    
    return [UIImage imageWithCIImage:ciImg];
}

上述方法生成的二维码是模糊的, 结合一下方法可以生成高清二维码:

/**
 *  根据CIImage生成指定大小的UIImage
 *
 *  @param image CIImage
 *  @param size  图片宽度
 *
 *  @return 生成高清的UIImage
 */
- (UIImage *)creatNonInterpolatedUIImageFormCIImage:(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图片
    CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
    CGContextRelease(bitmapRef);
    CGImageRelease(bitmapImage);
    return [UIImage imageWithCGImage:scaledImage];
}

将上述生成高清二维码的方法封装成UIImage的Category如下

.h 文件

#import <UIKit/UIKit.h>

@interface UIImage (Category)

/**
 *  根据CIImage生成指定大小的UIImage
 *
 *  @param image CIImage
 *  @param size  图片宽度
 *
 *  @return 生成的高清的UIImage
 */
+ (UIImage *)creatNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat)size;

@end

.m 文件

#import "UIImage+Category.h"

@implementation UIImage (Category)
/**
 *  根据CIImage生成指定大小的UIImage
 *
 *  @param image CIImage
 *  @param size  图片宽度
 *
 *  @return 生成的高清的UIImage
 */
+ (UIImage *)creatNonInterpolatedUIImageFormCIImage:(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图片
    CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
    CGContextRelease(bitmapRef);
    CGImageRelease(bitmapImage);
    return [UIImage imageWithCGImage:scaledImage];
}
@end

扫描二维码

1. 导入<AVFoundation/AVFoundation.h>

2. 扫描二维码实现

#import "ViewController.h"
// 导入<AVFoundation/AVFoundation.h>框架
#import <AVFoundation/AVFoundation.h>

@interface ViewController ()<AVCaptureMetadataOutputObjectsDelegate>
/** 捕捉会话 */
@property (nonatomic, weak) AVCaptureSession *session;
/** 预览图层 */
@property (nonatomic, weak) AVCaptureVideoPreviewLayer *layer;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    // 扫描二维码
    [self scanCIQRCode];
}

/**
 *  扫描二维码
 */
- (void)scanCIQRCode
{
    // 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. 添加输出数据接口
    AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init];
    // 设置输出接口代理
    [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)
    // 注意，这里必须设置在addOutput后面，否则会报错
    [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];
}

#pragma mark - <AVCaptureMetadataOutputObjectsDelegate>

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
    if (metadataObjects.count) {// 扫描到了数据
        AVMetadataMachineReadableCodeObject *object = [metadataObjects lastObject];

        // 停止扫描
        [self.session stopRunning];

        // 将预览图层移除
        [self.layer removeFromSuperlayer];
    }else{
        NSLog(@"没有扫描到数据");
    }
}

@end

参考文章