I'm not familiar with MATLAB's PSO toolbox, but you could save *every* fitness evaluation from within fitness function. In the postprocessing, the "fitness of each iteration" is a minimal/maximal fitness of set of $n$ entries ($n$ is swarm size).

$F_i = min(f_{i*(n-1)}, f_{i*(n-1)+1}, f_{i*(n-1)+2}, ... , f_{i*(n)-1}$

where $f$ is vector of fitness for all evaluated particles, $n$ is swarm size and $i$ is iteration index. If you want "overall best fitness up to $i$-th iteration", just additional do $F_i = min(F_i, F_{i-1})$.

Hope this helps...

In the attachment you can find an example of PSO  mat file. May be you can use it instead of using toolbox.

Thanks @Stefan Ivić for your answer. But I can't make changes in the MATLAB toolbox. MATLAB program prevent you from doing that.

Dear Ibrahim,

You have to code the PSO in matlab and then save the value of the fitness function by yourself. In stead of starting from scratch, you can try my code (attached). If you have any clarification in the code, do not hesitate to contact me.

Regards,

Mahmoud