Question

I ve got an c-struct array, and want to define a property. Here is the relative code..

struct Vertex {
    float x, y, z;
    float nx, ny, nz;
    float u, v;
};

@interface Mesh : NSObject{
    Vertex m_vertices[MaxVertices];
}
@property (nonatomic) Vertex m_vertices[MaxVertices];
@end

@implementation Mesh;
@synthesize m_vertices[MaxVertices];
@end

I first wrote like this with an error. how to set the property with c-struct array, or customlize the setter and getter? Any tips will be appreciated!

Answer 1

我离这里很近

typedef struct _Vertex {
float x, y, z;
float nx, ny, nz;
float u, v;
} Vertex;

#define MaxVertices 5

@interface Mesh : NSObject{
    Vertex m_verticesX[MaxVertices];
    Vertex *m_vertices;
}
@property (nonatomic) Vertex *m_vertices;
@end

@implementation Mesh;
@synthesize m_vertices;
- (Vertex *)m_vertices
{
    if (!m_vertices)
        m_vertices = m_verticesX;
    return m_vertices;
}
@end

希望能帮上忙

Answer 2

使用使用

@property (nonatomic) Vertex *m_vertices;

和

@synthesize m_vertices;

instead. You can t use a static array like this; malloc() it using something like this in your constructor 和 free() in the destructor:

- (id)init
{
    if ((self = [super init]))
    {
        m_vertices = malloc(sizeof(*m_vertices) * NUM_OF_VERTICES);
    }
    return self;
}

- (oneway void)dealloc
{
    free(m_vertices);
    [super dealloc];
}

Answer 3

您不能将数组用作属性。您可以做两件事 :

(1) 使用非国家行为者或NSMubableAray来屏蔽物体而不是支架。

或

(2) 将数组置于结构中:

typedef struct VertexArray
{
    struct Vertex m_vertices [MaxVertices];
};

@property (nonatomic, assign) VertexArray* m_vertices;

或

(3) (3) 将数组放入对象

@interface VertexArray
{
    struct Vertex m_vertices [MaxVertices];
}

- (struct Vertex)getVertexofIndex:(NSUInteger)index;
- (void)setVertex:(struct Vertex)vertex atIndex:(NSUInteger)index;

@end

and f或 the property in Mesh:

@property (nonatomic, retain) VertexArray* m_vertices;

或 you can put the contents of VertexArray directly within Mesh (i.e. the member variable and two access或 methods).

Answer 4

当返回 C 中的数组( 任何类型) 时,您要返回数组的第一个索引。

所以,如果我想返回下面的变量, 在接口中声明的变量。

 Vertex m_vertices[MaxVertices];

我可以说...

- (Vertex *)m_vertices
{
    return m_vertices;
}

上面说的和上面说的一模一样...

- (Vertex *)m_vertices
   {
       return &m_vertices[0];
   }

如果您想要返回整个阵列, 这样做的最好方法可能是使用Memcpy指令。

memcpy(<#void *#>, <#const void *#>, <#size_t#>)

此处参引:http://www.cplusplus.com/reference/cstring/memcpy/

像这样写入函数...

- (Vertex *)m_vertices
{
   Vertex *localVertex;
   memcpy(localVertex,&m_vertices,sizeof(Vertex)* MaxVertices);
   return localVertex;
}

这复制了字面字节, 并且非常快。它会返回整个阵列。

这样做的最好方式是使这种功能也有可能发挥。

- (Vertex *)m_vertices_nthIndex:(int)index
{
   return(&m_vertices[index]);
}

这样你就可以得到你需要的东西的索引了

友情链接