Question

我正在为这个问题寻找好的解决方案。我需要大约20多个字符串常量（资源文件名）。但我需要：

组常量（文件名）
迭代选定的常量组
按ID

所以我找到的最佳解决方案是为每个具有常量值和id的组创建常量NSDictionary。我想使用enum来存储常量ID，但是int不能在NSDictionary中用作键。

typedef enum {
    kSoundColorSelection1 = 0,
    kSoundColorSelection2,
    kSoundColorSelection3,
    kSoundFill1,
    kSoundFill2,
    kSoundSizeSelectionBig,
    kSoundSizeSelectionMedium
} ACSoundId;

“最简单”方式明确地将int转换为NSNumber

templatesSounds = [[NSDictionary alloc] initWithObjectsAndKeys:@"album_close.caf",[NSNumber numberWithInt:kSoundAlbumClose],
                 @"album_open.caf", [NSNumber numberWithInt:kSoundAlbumOpen], nil];

在这种情况下还有其他方法可以保持常量吗？谢谢！

Answer 1

有两种方法可以使这更容易。

解决方案1  如果您使用ACSoundId作为NSDictionary的键，您可以使用NSArray：

typedef enum {
    kSoundColorSelection1      = 0,
    kSoundColorSelection2      = 1,
    kSoundColorSelection3      = 2,
    kSoundFill1                = 3,
    kSoundFill2                = 4,
    kSoundSizeSelectionBig     = 5,
    kSoundSizeSelectionMedium  = 6
} ACSoundId;

按照上述枚举中定义的顺序将声音存储在数组中：

templatesSounds = [[NSArray alloc] initWithObjects:@"color_selection1.caf",
    @"color_selection2.caf",
    @"color_selection3.caf",
    @"color_fill1.caf",
    @"color_fill2.caf",
    @"size_selection_big.caf",
    @"size_selection_medium.caf",
    nil];

由于声音的索引与枚举的值相关，因此它的工作方式类似于NSDirectory：

queuedSound = [templatesSounds objectAtIndex:kSoundColorSelection2];

解决方案2 或者，您可以创建一个类别，以便更容易将整数用作NSDictionary中的键：

定义类别：

@interface NSMutableDictionary (NSNumberDictionary)
- (void) setObject:(id)anObject forNumber:(NSInteger)aNumber;
- (void) removeObjectForNumber:(NSInteger)aNumber;
- (id)   objectForNumber:(NSInteger)aNumber;
@end

实施类别：

@implementation NSMutableDictionary (NSNumberDictionary)
- (void) setObject:(id)anObject forNumber:(NSInteger)aNumber
{
   NSNumber * number;
   number = [[NSNumber alloc] initWithInteger:aNumber];
   [self setObject:anObject forKey:number];
   [number release];
   return;
}
- (void) removeObjectForNumber:(NSInteger)aNumber
{
   NSNumber * number;
   number = [[NSNumber alloc] initWithInteger:aNumber];
   [self removeObjectForKey:number];
   [number release];
   return;
}
- (id) objectForNumber:(NSInteger)aNumber
{
   NSNumber * number;
   id         object;
   number = [[NSNumber alloc] initWithInteger:aNumber];
   object = [self objectForKey:number];
   [number release];
   return(object);
}
@end

使用类别：

templatesSounds = [[NSMutableDictionary alloc] initWithWithCapacity1];
[templatesSounds setObject:@"color_selection1.caf" forNumber:kSoundColorSelection1];
[templatesSounds setObject:@"color_selection2.caf" forNumber:kSoundColorSelection2];
[templatesSounds setObject:@"color_selection3.caf" forNumber:kSoundColorSelection3];
[templatesSounds setObject:@"color_fill1.caf"      forNumber:kSoundColorFill1];
[templatesSounds setObject:@"color_fill2.caf"      forNumber:kSoundColorFill2];

Answer 2

如果你的“键”总是整数，为什么不使用普通的C数组？

NSString **templatesSounds ;

int numConstants = 10;
templatesSounds = calloc(numConstants , sizeof(NSString*));

templatesSounds[kSoundAlbumOpen] = @"album_open.caf";

NSString* soundName = templatesSounds [kSoundSizeSelectionMedium];

//...
free (templatesSounds);

带字符串常量和ID的NSDictionary

2 个答案: