Adding curl library in C project in Xcode

Steps:

1. Click over the project name in Xcode.

2. Go to "Build Phases" and expand "Link Binary with Libraries".

3. Click "+" sign and "Add Other". 

4. Click "Shift" + "Command" + "G". This will launch a folder select dialogue.

5. Go to "/usr/lib" and then select "libcurl.dylib".