CODEWITHSUNDEEP
cocoafoundationnsindexset
hertopnerd
hertopnerd

Reputation: 648

How to use NSIndexSet

In Objective-C, my program opens a window and displays a table. I want to have a specified row of the table highlighted.

How do I do this?

I seem to need the code

[myTableView selectRowIndexes:(NSIndexSet *) byExtendingSelection:(BOOL)];

I looked at the developer documentation, and figured out that the BOOL should be NO.

By looking at the NSIndexSet docs, I can't figure out what the right syntax should be.

Upvotes: 32

Views: 47344

Answers (4)

Richard
Richard

Reputation: 3386

Printing out an NSIndexSet in the debugger will show you that they are internally NSRanges. To create one, you can either specify the range or a single explicit index (from which it will create the range); something like

NSIndexSet *indexes = [[NSIndexSet alloc] initWithIndex:rowToHighlight];
[myTableView selectRowIndexes:indexes byExtendingSelection:NO];
[indexes release];

Note that the index(es) must all be unsigned integers (NSUIntegers, specifically).

Upvotes: 5

holex
holex

Reputation: 24041

it would be the proper way:

NSIndexSet *indexSet = [NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0, 3)];

or you can use the NSMutableIndexSet for the random indexes:

NSMutableIndexSet *mutableIndexSet = [[NSMutableIndexSet alloc] init];
[mutableIndexSet addIndex:0];
[mutableIndexSet addIndex:2];
[mutableIndexSet addIndex:9];

etc.

Upvotes: 82

Peter Hosey
Peter Hosey

Reputation: 96393

I seem to need the code

[myTableView selectRowIndexes:(NSIndexSet *) byExtendingSelection:(BOOL)];

No; those are casts without anything to cast, which is invalid.

Remove the casts and put values there instead.

I looked at the developer documentation, and figured out that the BOOL should be NO.

Yes, because you don't want to extend the selection, you want to replace it.

By looking at the NSIndexSet docs, I can't figure out what the right syntax should be.

The same as for passing any other variable or message expression.

You need to create an index set and then either stash it in a variable and pass that or pass the result of the creation message directly.

Upvotes: 0

Paul Schreiber
Paul Schreiber

Reputation: 12599

I'd use a factory method to avoid having to manage memory:

[myTableView selectRowIndexes:[NSIndexSet indexSetWithIndex:indexes] 
         byExtendingSelection:NO];

Upvotes: 4

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