原生根据URL创建二维码

创建二维码

- (CIImage *) creatQRCodeWithURL:(NSString *)urlStr {
    // 1. 实例化二维码滤镜
    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    // 2. 恢复滤镜的默认属性
    [filter setDefaults];
    // 3. 将字符串转换成
    NSData *data = [urlStr dataUsingEncoding:NSUTF8StringEncoding];
    // 4. 通过KVO设置滤镜inputMessage数据
    [filter setValue:data forKey:@"inputMessage"];
    // 5. 获得滤镜输出的图像
    CIImage *outputImage = [filter outputImage];
    return outputImage;
}

改变二维码大小

- (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size {
    
    CGRect extent = CGRectIntegral(image.extent);
    CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));
    
    // 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);
    
    // 保存bitmap到图片
    CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
    CGContextRelease(bitmapRef);
    CGImageRelease(bitmapImage);
    
    return [UIImage imageWithCGImage:scaledImage];
}