iOS 生成二维码图片

一个特别简易的生成二维码的功能
不需要添加任何库

/*
 生成二维码图片
 codeUrl:链接
 image_W:图片宽度
 retrun:二维码图片
 */
+(UIImage *)QRCodeGenerate:(NSString*)codeUrl imageWidth:(CGFloat)image_W{
    //生成二维码
    // 1. 创建一个二维码滤镜实例(CIFilter)
    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    // 滤镜恢复默认设置
    [filter setDefaults];
    
    // 2. 给滤镜添加数据
    NSData *data = [codeUrl dataUsingEncoding:NSUTF8StringEncoding];
    [filter setValue:data forKeyPath:@"inputMessage"];
    
    // 3. 生成高清二维码
    CIImage *image = [filter outputImage];
    
    CGRect extent = CGRectIntegral(image.extent);
    CGFloat scale = MIN(image_W/CGRectGetWidth(extent), image_W/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];
}

附加小功能---
判断图片中是否有二维码图片

+ (BOOL)IsThereQRCode:(UIImage *)codeImage{
    CIImage *detectImage = [CIImage imageWithData:UIImagePNGRepresentation(codeImage)];
    CIDetector *detector = [CIDetector detectorOfType:CIDetectorTypeQRCode context:nil options:@{CIDetectorAccuracy: CIDetectorAccuracyLow}];
    CIQRCodeFeature *feature = (CIQRCodeFeature *)[detector featuresInImage:detectImage options:nil].firstObject;
    if (feature.messageString) {
        return YES;
    }else{
        return NO;
    }
}