ios 將url通過CIFilter濾鏡生成條形碼和二維碼

一、生成條形碼

+ (UIImage *)barCodeImageWithUrl:(NSString *)url
{
    // 1.將字符串轉換成NSData
    NSData *data = [url dataUsingEncoding:NSUTF8StringEncoding];
    
    // 2.創建條形碼濾鏡
    CIFilter *filter = [CIFilter filterWithName:@"CICode128BarcodeGenerator"];
    
    // 3.恢復濾鏡的默認屬性
    [filter setDefaults];
    
    // 4.設置濾鏡inputMessage數據
    [filter setValue:data forKey:@"inputMessage"];
    
    // 5.獲得濾鏡輸出的圖像
    CIImage *urlImage = [filter outputImage];
    
    // 6.將CIImage 轉換爲UIImage
    UIImage *image = [UIImage imageWithCIImage:urlImage];
    
    return image;
}

二、生成二維碼

+ (UIImage *)twoDimensionCodeWithUrl:(NSString *)url
{
    // 1.將字符串轉換成NSData
    NSData *data = [url dataUsingEncoding:NSUTF8StringEncoding];
    
    // 2.創建二維碼濾鏡
    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    
    // 3.恢復默認
    [filter setDefaults];
    
    // 4.給濾鏡設置數據
    [filter setValue:data forKeyPath:@"inputMessage"];
    
    // 5.獲取濾鏡輸出的二維碼
    CIImage *outputImage = [filter outputImage];
    
    // 6.此時生成的還是CIImage，可以通過下面方式生成一個固定大小的UIImage
    CGFloat size = 200;
    CGRect extent = CGRectIntegral(outputImage.extent);
    CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));
    
    // 7.創建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:outputImage fromRect:extent];
    CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);
    CGContextScaleCTM(bitmapRef, scale, scale);
    CGContextDrawImage(bitmapRef, extent, bitmapImage);
    
    // 8.保存bitmap到圖片
    CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
    CGContextRelease(bitmapRef);
    CGImageRelease(bitmapImage);
    return [UIImage imageWithCGImage:scaledImage];
}