To search for text foo within a {} block surrounding the cursor use the following command (<ESC> - escape key, <CR> - enter key) :
vi{<ESC>/\%Vfoo<CR>
now you can jump between the matches within the block by pressing n and p. If you have hlsearch option enabled this will highlight all the matches.
\%V is a special search pattern part, that tells vim to search only in the visually selected area. You can also make a mapping like this:
:vnoremap g/ <ESC>/\%V
After this the above command is shortened to the following:
vi{g/foo<CR>
Another useful trick is to print all the lines containing the pattern:
vi{
:'<,'>g/foo/#
The '<,'> range is inserted automatically.
See :help range and :help :g.