排序一个NSArray并与第二个数组匹配顺序？

Question

I have two NSMutabeArrays, one full of numbers, the other full of words.

Lets say the two arrays look like this:

1  hello
24 no
11 there
5  boo

Now I order the first array so the numbers are descending (and as below I want the words to move with the numbers so they stay with the original number they are associated with):

24 no
11 there
5  boo
1  hello

Any idea how I can achieve this? Thanks.

Answer 1

You should combine the numbers and words into a single object that has properties for both. You can then maintain an ordered array of those objects rather than trying to coordinate two independent arrays.

One way to achieve this is with a NSDictionary , but I typically recommend a trivial model object to hold the two values:

@interface SomeObject : NSObject
@property (nonatomic, readwrite, strong) NSString *word;
@property (nonatomic, readwrite, assign) NSUInteger number;
@end

@implementation SomeObject
@synthesize word=_word;
@synthesize number=_number;
@end

There are other ways to build this object (you could make it immutable for instance, which is good for multi-threaded apps), but this is the simplest.

Answer 2

These two arrays are obviously very tightly coupled, so you want to reflect this coupling in the program design, and not just have it buried in the implementation of the sort routine. How best to do this depends on the context you have to fit the solution into. The single array solution may be best, or it may not. Another possible solution is to create a new class that contains the two arrays and is responsible for maintaining their consistency when sorting, inserting, deleting etc.

Answer 3

While not the most optimal answer, but certainly a way I have implemented multi-column tables (sortable by any column).

I did mine this way so that the code itself would be more transportable between platforms.

the way to do this would be to hold an index mapping array. The way this works is, you have dataArray1 and dataArray 2. If you want to sort by dataArray1, then you hold the new mapped indeces (as you are sorting the dataArray1) in the mapping array. After you have finished sorting, the data held by the mapping array will be the index from the dataTable2 that needs to be placed in the position of the index of the mapping array.

I see a lot of answers that talk about coupling of the data. This heavily depends on how you really intend to use the data. In my design, the data needed coupling only when shown in the table view (and for display of the table), but within my graph view, the data ordering didnt in this manner didnt matter, so no coupling was needed. I think there are many good answers here, the question is what are designing around this data???