生成二维码图片

示例代码：

- (void)click
{    
    UIImage *image = [self imageQrcodeWithMessage:@"http://www.hao123.com" withSize:200.0f];
    UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
    [self.view addSubview:imageView];
    imageView.frame = CGRectMake((self.view.frame.size.width - 200.0f) / 2, 20.0, 200.0f, 200.0f);
}

生成效果：

二维码生成图片.png

// 生成二维码
- (UIImage *)imageQrcodeWithMessage:(NSString *)qrString withSize:(CGFloat) size
{
    // Need to convert the string to a UTF-8 encoded NSData object
    NSData *stringData = [qrString dataUsingEncoding:NSUTF8StringEncoding];
    // Create the filter
    CIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    // Set the message content and error-correction level
    [qrFilter setValue:stringData forKey:@"inputMessage"];
    [qrFilter setValue:@"M" forKey:@"inputCorrectionLevel"];
    
    CGRect extent = CGRectIntegral(qrFilter.outputImage.extent);
    CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));
    // create a bitmap image that we'll draw into a bitmap context at the desired size;
    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:qrFilter.outputImage fromRect:extent];
    CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);
    CGContextScaleCTM(bitmapRef, scale, scale);
    CGContextDrawImage(bitmapRef, extent, bitmapImage);
    // Create an image with the contents of our bitmap
    CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
    // Cleanup
    CGContextRelease(bitmapRef);
    CGImageRelease(bitmapImage);
    return [UIImage imageWithCGImage:scaledImage];
}