NSData *videodata=-----?

NSString *urlstring = [[NSString alloc] initWithData:videodata encoding:NSUTF8StringEncoding] ;

NSString *urlstring= [NSString stringWithUTF8String:[videodata bytes]];

NSData *somedata = [NSData data];
NSString *str = [[NSString alloc] initWithData:somedata encoding:NSUTF8StringEncoding];