第一步：

第二步：

第三步：

注：程式碼複製區域

- (void)viewDidLoad {
    [super viewDidLoad];
    
    NSString *url = @"http://www.baidu.com";

    UIImageView *imageView = [[UIImageView alloc] init];
    imageView.image = [self method2:[self method1:url] size:200];
    imageView.bounds = CGRectMake(0, 0, 200, 200);
    imageView.center = self.view.center;
    [self.view addSubview:imageView];
}

//生成二維碼，但模糊
- (CIImage *)method1:(NSString *)url {
    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    [filter setDefaults];
    NSData *data = [url dataUsingEncoding:NSUTF8StringEncoding];
    [filter setValue:data forKeyPath:@"inputMessage"];
    return [filter outputImage];
}

//模糊處理
- (UIImage *)method2:(CIImage *)image size:(CGFloat)size {
    CGRect extent = CGRectIntegral(image.extent);
    CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));
    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);
    CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
    CGContextRelease(bitmapRef);
    CGImageRelease(bitmapImage);
    return [UIImage imageWithCGImage:scaledImage];
}