ObjC：在循环中构造一个可变字典

Question

我觉得我已经阅读了许多（简单）例子，这些例子完全符合我所要做的。我似乎无法得到这个工作。我需要再次注意我的代码，并且我周围没有任何人，所以如果这看起来很简单，请原谅我......代码编译没有问题。谢谢！

@implementation Engine 
- (id) initWithInventory: (NSString *) path { 
    if (self = [super init]) { 
     NSString *contents = [NSString stringWithContentsOfFile:@"ingredientList.csv" encoding:NSASCIIStringEncoding error:nil]; 

     NSLog(@"%@",contents); // This yields the contents of the file appropriately 

     NSArray *lines = [contents componentsSeparatedByCharactersInSet:[NSCharacterSet newlineCharacterSet]]; 
     NSRange ingredientRange = {0,96}; // This is done because I want to omit the last element of the array... the 97th is an empty string caused by the end of file newline character. I know it's bad coding... 

     NSEnumerator *enumerator = [[lines subarrayWithRange:ingredientRange] objectEnumerator]; 
     NSString *curString; 
     NSArray *ingredientElements; 
     NSRange activeEffectRange = {1,4}; // Element 0 will be the key, elements 1-4 are the array to be stored. 

     while (curString = [enumerator nextObject]) { 
      ingredientElements = [curString componentsSeparatedByString:@","]; 
      Ingredient *theIngredient = [[Ingredient alloc] initWithName:[ingredientElements objectAtIndex:0] andActiveEffects:[ingredientElements subarrayWithRange:activeEffectRange]]; 
      NSLog(@"%@",[theIngredient ingredientName]); 
      NSLog(@"%@",[theIngredient activeEffects]); //These both print out correctly. 

      NSString *theName = [theIngredient ingredientName]; 
      [allIngredients setObject:theIngredient forKey:theName]; 
      NSLog(@"%@",[allIngredients objectForKey:[theIngredient ingredientName]]); // ***This yields (null)*** 
     } 
    } 
    return self; 
} 

编辑：我要补充一点，allIngredients是正在启动的类的实例变量，所以它被正确定义为NSMutableDictionary：

@interface Engine : NSObject { 
    NSMutableDictionary *allIngredients; 
} 
- (id) initWithInventory: (NSString *) path; 
@end 

Answer 1

你在哪里创建allIngredients？你已经声明了它，但是在你使用它之前你还没有分配它。

allIngredients = [[NSMutableDictionary alloc] init]