NSString与int与Float互转

• NSString转int或float
  NSString *userid = @"1234";
  NSString *username = @"5678.0";
  int iduser = [userid intValue];
  float name = [username floatValue];
  //切记不能使用强转
  int iduser = (int)userid;
  foalt name = (float)username;
  //这样转换的结果是错误的，有可能是内存地址。

• int或float转NSString
  NSString *user_id = [NSString stringWithFormat:@"%d", userid];
  NSString *user_name = [NSString stringWithFormat:@"%f",username];