opencv/doc/tutorials/ios/hello/hello.markdown

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OpenCV iOS Hello {#tutorial_hello}
================
@next_tutorial{tutorial_image_manipulation}
Goal
----
In this tutorial we will learn how to:
- Link OpenCV framework with Xcode
- How to write simple Hello World application using OpenCV and Xcode.
Linking OpenCV iOS
------------------
Follow this step by step guide to link OpenCV to iOS.
-# Create a new XCode project.
-# Now we need to link *opencv2.framework* with Xcode. Select the project Navigator in the left
hand panel and click on project name.
-# Under the TARGETS click on Build Phases. Expand Link Binary With Libraries option.
-# Click on Add others and go to directory where *opencv2.framework* is located and click open
-# Now you can start writing your application.
![](images/linking_opencv_ios.png)
Hello OpenCV iOS Application
----------------------------
Now we will learn how to write a simple Hello World Application in Xcode using OpenCV.
- Link your project with OpenCV as shown in previous section.
- Open the file named *NameOfProject-Prefix.pch* ( replace NameOfProject with name of your
project) and add the following lines of code.
@code{.m}
#ifdef __cplusplus
#import <opencv2/opencv.hpp>
#endif
@endcode
![](images/header_directive.png)
- Add the following lines of code to viewDidLoad method in ViewController.m.
@code{.m}
UIAlertView * alert = [[UIAlertView alloc] initWithTitle:@"Hello!" message:@"Welcome to OpenCV" delegate:self cancelButtonTitle:@"Continue" otherButtonTitles:nil];
[alert show];
@endcode
![](images/view_did_load.png)
- You are good to run the project.
Output
------
![](images/ios_hello_output.png)
Changes for XCode5+ and iOS8+
-----------------------------
With the newer XCode and iOS versions you need to watch out for some specific details
- The *.m file in your project should be renamed to *.mm.
- You have to manually include AssetsLibrary.framework into your project, which is not done anymore by default.