将对象添加到NSMutableArray属性

Question

这是我的数据结构:

group [1...n] {
  id,
  name,
  elements : [1...n]
}

我为具有所有属性的元素定义了一个类,为group定义了一个类:

@interface Group : NSObject {    
    NSInteger groupID;
    NSString *groupName;        
    NSMutableArray *elements;       
}

@property (assign, readwrite) NSInteger groupID;
@property (assign, readwrite) NSString *groupName;
@property (assign, readwrite) NSMutableArray *elements;

和单个元素:

@interface Element : NSObject {
    NSInteger elementID;
    NSString *elementName;
}
@property (assign, readwrite) NSInteger elementID;
@property (assign, readwrite) NSString *elementName;

这两个类都有属性和综合.当应用程序启动时,我在数据结构上插入数据:

arrGroup = [NSMutableArray array];
[arrGroup retain];
Element *element1 = [[Element alloc] init];
element1.elemenID = 1;
element1.elemenName = @"Andrea";

Element *element = [[Element alloc] init];
element2.elementID = 2;
element2.elementName = @"Andrea2";

Group *group = [[Group alloc] init];    
group.groupID = 1;
group.groupName = @"Grup 1";    
[group.elements addObject:element1];
[group.elements addObject:element2];

[contact1 release];
[contact2 release];

[arrGroup addObject:group];

问题是[group.elements addObjct:element1].在NSMutableArray元素上没有写任何内容.

你能帮我找到错误吗？有一种更好的方法来检索结构数据(elemens组)？

感谢帮助!安德里亚

Answer 1

@synthesize 只为您的属性生成getter和setter,如果需要,您必须自己处理初始化.

要初始化可变数组,请在初始化程序中执行此操作:

- (id)init { // or however it is named
    if ((self = [super init])) {
        elements = [[NSMutableArray alloc] init];
        // ... more?
    }
    return self;
}

- (void)dealloc {
    [elements release]; // don't forget to clean up
    // ... more?
    [super dealloc];
}