创建只包含给定类的对象的数组 [英] Creating an array that contains only objects of a given class

问题描述

好的，所以我有下面的代码（Objective-C FYI），我想知道如果我想创建一个NSMutableArray c_data 对象，我将如何去这样做？它有点类似于声明一个 List< c_data>

  @interface c_data：NSObject {
 double值; 
 int label; 
 int ID; 
} 
 @property double value; 
 @property int label; 
 @property int ID; 
 
  - （c_data *）init; 
  - （c_data *）initWithValue：（double）value; 
 @end 
 
 @implementation c_data 
 @synthesize值，label，ID; 
  - （c_data *）init {
 return self; 
} 
  - （c_data *）initWithValue：（double）val {
 value = val; 
 return self; 
} 
 @end 
  

如果你看看 feat_data ，我试图使 cData 数组 c_data 。我已经包括我的尝试，但我不认为这是正确的，因为 c_data 不是一个数组。有什么建议么？

  @interface feat_data：NSObject {
 NSMutableArray * nData; 
 NSMutableArray * cData; 
 char类型; 
} 
 @property（nonatomic，retain）NSMutableArray * nData; 
 @property（nonatomic，retain）NSMutableArray * cData; 
 @property char type; 
  - （feat_data *）init; 
 @end 
 
 @implementation feat_data 
 @synthesize nData，cData，type; 
  - （feat_data *）init {
 nData = [[NSMutableArray alloc] init]; 
 c_data * c_dataInstance = [[c_data alloc] init]; 
 cData = [[NSMutableArray alloc] initWithArray：c_dataInstance]; 
 return self; 
} 
 @end 
  




解决方案

$ p> [NSMutableArray addObject：[[[c_data alloc] init] autorelease]];


未键入Objective-C数组。看来你有一些C ++不学习。

在一个相关的注释，你的inits是相当糟糕。您还需要调用super init，如下：

   - （id）init {
 self = [super在里面]; 
 if（self！= nil）{
 //在这里初始化。 
} 
 return self; 
} 
  

Ok, so I have the code below (Objective-C FYI) and I was wondering if I want to create an NSMutableArray of c_data objects, how would I go about doing that? It's sort of like declaring a List<c_data> cData in C#.

@interface c_data : NSObject {
    double value;
    int label;
    int ID;
}    
@property double value;
@property int label;
@property int ID;

-(c_data*) init;
-(c_data*) initWithValue:(double)value;    
@end

@implementation c_data
@synthesize value, label, ID;
-(c_data*) init {
    return self;
}
-(c_data*) initWithValue:(double)val {
    value = val;
    return self;
}
@end

If you look at the class feat_data, I'm trying to make cData an array of the class c_data. I have included my attempts at it, but I don't think it's right because c_data isn't an array. Any suggestions?

@interface feat_data : NSObject {
    NSMutableArray *nData;
    NSMutableArray *cData;
    char type;
}
@property(nonatomic, retain) NSMutableArray *nData;
@property(nonatomic, retain) NSMutableArray *cData;
@property char type;
-(feat_data*)init;
@end

@implementation feat_data
@synthesize nData, cData, type;
-(feat_data*)init {
    nData = [[NSMutableArray alloc] init];
    c_data *c_dataInstance = [[c_data alloc] init];
    cData = [[NSMutableArray alloc] initWithArray:c_dataInstance];
    return self;
}
@end

解决方案

[NSMutableArray addObject:[[[c_data alloc] init] autorelease]];

Objective-C arrays aren't typed. It seems you have some C++ unlearning to do.

On a related note, your inits are pretty bad. You need to call super init as well, as such:

- (id)init {
  self = [super init];
  if (self != nil) {
    //Initialize here.
  }
  return self;
}

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