Those who use chargers, which had not been blessed by Apple, found that after their upgrade to iOS 7 they did not work. The Tame Apple press claims that the move comes about because anything made in China, unblessed by Apple, is likely to kill you. This opposed to something that made in China by Apple, which is everything.
Apple’s cables contain a chip that authenticates the cable allowing it to be used with the device. Of course there is nothing to stop unauthorized cables with cracked chips and apparently these work fine with iOS 7. There are some work arounds if you do not want to spend cash and get an official one, but it is so complicated you might as well just by the Apple version.