Objective c NSOutlineView显示三个级别

我正在使用NSOutlineView，我想显示第四个子级别。现在我只能显示三个子级别

大纲视图控制器.m

 -(id)init{
     self = [super init];
     if(self){
         _people = [[NSMutableArray alloc]init];

         Person *quick = [[Person alloc]initWithName:@"First"];
         [quick addChild:[[Person alloc]initWithName:@"Second"]];
         [(Person *)[quick.children objectAtIndex:0]addChild:[[Person alloc]initWithName:@"Third"]];

         [_people addObject:quick];

     }
     return self; 
 }

人

-(id)init{
     return [self initWithName:@"Name"]; 
 }


 -(id)initWithName:(NSString *)name {
         self = [super init];
         if(self){
             _name = [name copy];
             _children = [[NSMutableArray alloc]init];

         }
         return self; 
     }

 -(void)addChild:(Person *)p {
     [_children addObject:p];
 }

人

 @property (copy)NSString *name;
 @property(readonly,copy)NSMutableArray *children;
 -(id)initWithName:(NSString *)name;
 -(void)addChild:(Person *)p;

我得到的输出是这样的

>First
   >Second
      Third

我想要这样的输出

>First
   >Second
      >Third
         >Fourth
            Fifth

---

谢谢。

您将在此处向second添加一个孩子：

[(Person *)[quick.children objectAtIndex:0]addChild:[[Person alloc]initWithName:@"Third"]];

类似地，您可以将子项添加到第三项：

[(Person*)[((Person *)[quick.children objectAtIndex:0]).children objectAtIndex:0]addChild:[[Person alloc]initWithName:@"Fourth"]];

然后是第四个：

 [(Person*)[((Person*)[((Person *)[quick.children objectAtIndex:0]).children objectAtIndex:0]).children objectAtIndex:0] addChild:[[Person alloc]initWithName:@"Fifth"]];

或者，为了简单起见，首先创建最低级别的对象，然后将其作为子对象添加到其父对象：

Person *fifth = [[Person alloc]initWithName:@"Fifth"]; 
Person *fourth = [[Person alloc]initWithName:@"Fourth"];
[fourth addChild: fifth];
Person *third = [[Person alloc]initWithName:@"Third"];
[third addChild: fourth];
Person *second = [[Person alloc]initWithName:@"Second"];
[second addChild: third];
Person *quick = [[Person alloc]initWithName:@"First"];
[quick addChild: second];

---

你要加三个孩子，这就是为什么你要加三级，再加一个孩子到第三级，再到第四级我知道怎么把孩子加到第三级？