如何生成二维码

- (void)createQrCode{

// 1.创建过滤器

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

// 2.恢复默认

[filter setDefaults];

// 3.给过滤器添加数据

NSData *data = [@"dgkajscbasbcva,nbv" dataUsingEncoding:NSUTF8StringEncoding];

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

//

//    // 4.获取输出的二维码

CIImage *outputImage = [filter outputImage];

//    // 5.显示二维码

UIImageView *qrcodeImageView = [[UIImageView alloc]init];

[self.view addSubview:qrcodeImageView];

qrcodeImageView.frame = CGRectMake(0, 64, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height-64);

qrcodeImageView.image = [self createNonInterpolatedUIImageFormCIImage:outputImage withSize:self.view.frame.size.height];

}

- (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);

CGColorSpaceRelease(cs);

UIImage* NewImage = [UIImage imageWithCGImage:scaledImage];

CGImageRelease(scaledImage);

return NewImage;

}