首先來(lái)看看借助蘋果原生CoreImage框架如何將文字信息生成二維碼圖片，毫無(wú)疑問(wèn)肯定要導(dǎo)入#import <CoreImage/CoreImage.h>這個(gè)頭文件。
實(shí)現(xiàn)以下代碼既可以生成二維碼圖片，但是圖片比較模糊。

// 1.創(chuàng)建濾鏡對(duì)象
    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    
    // 2.恢復(fù)默認(rèn)設(shè)置
    [filter setDefaults];
    
    // 3.設(shè)置數(shù)據(jù)
    NSString *info = @"http://www.baidu.com";
    NSData *infoData = [info dataUsingEncoding:NSUTF8StringEncoding];
    [filter setValue:infoData forKeyPath:@"inputMessage"];
    
    // 4.生成二維碼
    CIImage *outputImage = [filter outputImage];
    self.imageView.image = [UIImage imageWithCIImage:outputImage];

解決二維碼圖片模糊問(wèn)題，需要我們自己繪圖。新建一個(gè)CIImage的分類，然后實(shí)現(xiàn)如下代碼。直接調(diào)用這個(gè)分類的方法將CIImage轉(zhuǎn)為UIImage即可解決問(wèn)題。

- (UIImage *)createNonInterpolatedWithSize:(CGFloat)size
{
    CGRect extent = CGRectIntegral(self.extent);
    CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));
    
    // 1.創(chuàng)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:self fromRect:extent];
    CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);
    CGContextScaleCTM(bitmapRef, scale, scale);
    CGContextDrawImage(bitmapRef, extent, bitmapImage);
    
    // 2.保存bitmap到圖片
    CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
    CGContextRelease(bitmapRef);
    CGImageRelease(bitmapImage);
    return [UIImage imageWithCGImage:scaledImage];
}

接下來(lái)看看如何掃面二維碼。掃秒二維碼是借助AVFoundation框架，相關(guān)注釋在代碼中。

#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>
@interface ViewController ()<AVCaptureMetadataOutputObjectsDelegate>
//注意這里用weak
@property (nonatomic, weak) AVCaptureSession *session;
@property (nonatomic, weak) AVCaptureVideoPreviewLayer *layer;
@end
@implementation ViewController
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
    //1.獲取捕捉會(huì)話
    AVCaptureSession *session = [[AVCaptureSession alloc]init];
    self.session = session;
    //2.設(shè)置輸入（攝像頭）
    //AVMediaTypeVideo攝像頭, AVMediaTypeAudio話筒, or AVMediaTypeMuxed彈幕
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];
    [_session addInput:input];
    
    //3.設(shè)置輸出數(shù)據(jù)
    AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc]init];
    //設(shè)置代理  <AVCaptureMetadataOutputObjectsDelegate>
    [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    [_session addOutput:output];
    //設(shè)置輸出類型 AVMetadataObjectTypeQRCode表示輸出類型為二維碼
    //注意：必須在設(shè)置代理完畢后設(shè)置
    [output setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];
    
    //4.添加閱覽圖層
     AVCaptureVideoPreviewLayer *layer = [[AVCaptureVideoPreviewLayer alloc]initWithSession:self.session];
    self.layer = layer;
    _layer.frame = self.view.bounds;
    [self.view.layer addSublayer:_layer];
    //5.開(kāi)始掃描
    [_session startRunning];
}
#pragma mark - <AVCaptureMetadataOutputObjectsDelegate>
-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{
    if (metadataObjects.count > 0) {
         // 1.獲取掃描到的內(nèi)容
        AVMetadataMachineReadableCodeObject *object = [metadataObjects lastObject];
        NSLog(@"%@", object.stringValue);
        // 2.停止會(huì)話
        [self.session stopRunning];
        // 3.移除預(yù)覽圖層
        [self.layer removeFromSuperlayer];
    }
}