将字符串转换成类名，然后跳转

从字典中获的字符串，然后进行跳转

1 if ([dic objectOrNilForKey:@"jump"]) {//从字典取值
2         NSString *jumpString = [dic objectOrNilForKey:@"jump"];
3         Class  jumpClass = NSClassFromString(jumpString); //将字符串转变成类
4         id jumpVc = [[jumpClass alloc]init];//类进行实例化，接收用id
5         [self.navigationController pushViewController:jumpVc animated:YES];
6         return;
7     }