How to accept Xcode license?

I want to install a C based toolbox on MATLAB software. To do this, I need to install the GCC compiler. I think I have done that already. And I have Xcode too. To setup the toolbox, I need to write mex -setup; in the MATLAB command window. I've got the following warning and don't know how to solve it: > Warning: Xcode is installed, but its license has not been accepted. Run Xcode and accept its license agreement. > > Error using mex > No supported compiler or SDK was found. For options, visit http://www.mathworks.com/support/compilers/R2014a/maci64 .