//中文转成utf8
NSString *utf8 = [@"今晚打老虎" stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
//utf8转成中文
NSString *zhongwen = [utf8 stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSLog(@"utf8->%@",utf8);
NSLog(@"zhongwen->%@",zhongwen);