Is there any way to manually control which index we want to add our data to with an NSMutableArray? In PHP, for example, we can do:
$foo[2] = "fafa";
$foo[8] = "haha";
Can the manual assigning of indexing be done on NSMutableArray?
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4 Answers
NSMutableArrays are not sparse -- they cannot have gaps where no objects are stored. It is possible to insert an object at any index from 0 to length - 1, using insertObject:atIndex: (as Edu mentioned), but other than that you can only append objects (using addObject:).
If you need to associate objects with arbitrary integers, you can use an NSMapTable -- the functional interface allows integer keys, or simply use an NSMutableDictionary, with NSNumber keys (as drewag suggested).
See also: How to do sparse array in Cocoa
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Just because it's not entirely clear to me that TeamStar wants a sparse array, I'll just mention that you can assign objects to specific indexes within an NSMutableArray – so long as the array is already long enough – using -replaceObjectAtIndex:withObject: and the other -replace… methods.
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Joe Shamuraq
Well the reason is because the radio button i use is supposed to update the array row[] not add more data into the array in case the users decides to change the option...
No that is not possible. I would suggest using an NSMutableDictionary instead. You can use NSNumbers as indexes.
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- (void)insertObject:(id)anObject atIndex:(NSUInteger)index
Important Raises an NSRangeException if index is greater than the number of elements in the array.
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Costique
Raises an
NSRangeException if index is greater than the number of elements in the array.
Eduardo
You can use a for loop and fill the array with zeros. But I don't think i'ts a good idea so, have you tried NSMutableDictionary?
Joe Shamuraq
but isn't that making it into a function? can i use e.g.;
@property (nonatomic, copy) NSMutableArray *rangenans; followed by: [rangenans insertObject:label1.text atIndex:0];