1OpenCV iOS Hello {#tutorial_hello}
2================
3
4Goal
5----
6
7In this tutorial we will learn how to:
8
9-   Link OpenCV framework with Xcode
10-   How to write simple Hello World application using OpenCV and Xcode.
11
12Linking OpenCV iOS
13------------------
14
15Follow this step by step guide to link OpenCV to iOS.
16
17-#  Create a new XCode project.
18-#  Now we need to link *opencv2.framework* with Xcode. Select the project Navigator in the left
19    hand panel and click on project name.
20-#  Under the TARGETS click on Build Phases. Expand Link Binary With Libraries option.
21-#  Click on Add others and go to directory where *opencv2.framework* is located and click open
22-#  Now you can start writing your application.
23
24![](images/linking_opencv_ios.png)
25
26Hello OpenCV iOS Application
27----------------------------
28
29Now we will learn how to write a simple Hello World Application in Xcode using OpenCV.
30
31-   Link your project with OpenCV as shown in previous section.
32-   Open the file named *NameOfProject-Prefix.pch* ( replace NameOfProject with name of your
33    project) and add the following lines of code.
34    @code{.m}
35    #ifdef __cplusplus
36    #import <opencv2/opencv.hpp>
37    #endif
38    @endcode
39    ![](images/header_directive.png)
40
41-   Add the following lines of code to viewDidLoad method in ViewController.m.
42    @code{.m}
43    UIAlertView * alert = [[UIAlertView alloc] initWithTitle:@"Hello!" message:@"Welcome to OpenCV" delegate:self cancelButtonTitle:@"Continue" otherButtonTitles:nil];
44    [alert show];
45    @endcode
46    ![](images/view_did_load.png)
47
48-   You are good to run the project.
49
50Output
51------
52
53![](images/output.png)
54
55Changes for XCode5+ and iOS8+
56-----------------------------
57
58With the newer XCode and iOS versions you need to watch out for some specific details
59
60-   The *.m file in your project should be renamed to *.mm.
61-   You have to manually include AssetsLibrary.framework into your project, which is not done anymore by default.
62