想NSArray的valueForKey返回數組索引

Question

我可以創建一個包含myArray對象的所有哈希值這樣的NSArray：

NSArray *a = [myArray valueForKey:@"hash"]; 

我傳遞給valueForKey:什麼鍵獲得一個數組包含myArray的索引？

說myArray有n項。我想要做這樣的事情：

NSArray *a = [myArray valueForKey:@"index"]; 

Answer 1

NSArray * arrayWithNumbersInRange(NSRange range) 
{ 
    NSMutableArray * arr = [NSMutableArray array]; 
    NSUInteger i; 
    for(i = range.location; i <= range.location + range.length; i++){ 
     [arr addObject:[NSNumber numberWithUnsignedInteger:i]; 
    } 

    return arr; 
} 

---

NSArray * indexArray = arrayWithNumbersInRange((NSRange){0, [myArray length]-1}); 

Answer 2

您可以查詢一個NSArray爲對象的指數與indexOfObject:

NSArray *a = [myArray valueForKey:@"hash"]; 
NSInteger index = [myArray indexOfObject:a]; 

Answer 3

創建的超NSArray返回索引：

// 
// CapArrayOfIndex.h 
// Created by carmin politano on 7/26/12. 
// no rights reserved 
// 

@interface CapArrayOfIndex : NSArray { 
    /*! Simulated constant array containing an array of NSNumber representing the index. */ 
    NSUInteger iCount; 
    //*! NSNotFound causes bybass of index bounds testing. */ 
} 
#pragma mark create 
+ (CapArrayOfIndex*) withCount: (NSUInteger) aCount; 
@end 

和

// 
// CapArrayOfIndex.mm 
// Created by carmin on 7/26/12. 
// no rights reserved 
// 

#import "CapArrayOfIndex.h" 

@implementation CapArrayOfIndex 
#pragma mark NSCopying 
- (id) copyWithZone: (NSZone*) aZone { 
    /*! New allocation required because -count is a mutable property. */ 
    return [CapArrayOfIndex withCount: self.count]; 
} 
#pragma mark create 
+ (CapArrayOfIndex*) withCount: (NSUInteger) aCount { 
    CapArrayOfIndex* zArray = self.alloc; 
    zArray->iCount = aCount; 
    return zArray; 
} 
#pragma mark NSArray 
- (NSUInteger) count { 
    return iCount; 
} 
- (void) setCount: (NSUInteger) aCount { 
    iCount = aCount; 
} 
- (id) objectAtIndex: (NSUInteger) aIndex { 
    /*! My code performs a bounds test using unusual macros: return [ViaUInteger RaiseIfObjectAtIndex(nil, self, aIndex, nil)]; */ 
    return [NSNumber numberWithInteger: aIndex]; 
} 
@end