Xcode 7 and openCV (no Swift): Core.hpp header must be compiled as C++
<p>I have followed the <a href="http://docs.opencv.org/2.4/doc/tutorials/ios/video_processing/video_processing.html#example-video-frame-processing-project" rel="noreferrer">instructions</a> on how to install OpenCV on an iOS project. However when using Xcode 7 I had to add manually a prefix header. Doing this unfortunately did not help and I was still getting compile errors. I then read another post suggesting that is best to add manually the imports and not use prefix headers in Xcode 7, so I did.</p>

<p>Here is my code:</p>

<pre><code>#import "ViewController.h"

#import &lt;opencv2/opencv.hpp&gt;
#import &lt;UIKit/UIKit.h&gt;
#import &lt;Foundation/Foundation.h&gt;
#import &lt;opencv2/highgui/cap_ios.h&gt;
//using namespace cv;

@interface ViewController ()
{
    IBOutlet UIImageView* imageView;
    IBOutlet UIButton* button;
}

- (IBAction)actionStart:(id)sender;

@end
</code></pre>

<p>However I still get the following errors. </p>

<p><a href="https://i.stack.imgur.com/7AN4B.png" rel="noreferrer"><img src="https://i.stack.imgur.com/7AN4B.png" alt="enter image description here"></a>
<a href="https://i.stack.imgur.com/rqCoT.png" rel="noreferrer"><img src="https://i.stack.imgur.com/rqCoT.png" alt="enter image description here"></a></p>

<p>When I uncomment the using namespace cv; I get the following:</p>

<p><a href="https://i.stack.imgur.com/VyUDH.png" rel="noreferrer"><img src="https://i.stack.imgur.com/VyUDH.png" alt="enter image description here"></a></p>

<p>I found some complex solutions talking about exposing headers to Swift etc.. I just want my project to work on Objective-C with Xcode 7 ... </p>