That's precisely the point: the swaps have one leg denominated in dollars, but they are settled in reals.

FT.com: Brazil: net debtor to the world

When the bank uses such a swap to limit the depreciation of the real, it offers to pay the difference between the initial exchange rate and the final exchange rate during the period of the contract, plus a dollar-linked rate of interest (known to traders as the cupom cambial). In return, it receives the cumulative interbank interest rate (currently about 10 per cent a year) on the amount of the contract in Brazilian reals. Crucially, the contracts are settled entirely in reals. No dollars exchange hands and there is no obvious impact on the country's ability to pay its foreign debts.

A society committed to the notion that government is always bad will have bad government. And it doesn't have to be that way. — Paul Krugman