Question

I am adding objects (NSNumbers in this case) to an NSMutableArray and I wanted to check what the best way is to check for duplicates in the array before adding. (i.e.)

Number to add
if (NSMutableArray does not contain Number) {
    add Number
}

EDIT:

Many thanks, I had a good luck at NSArray this morning but totally missed “containsObject”. That would have done just fine, but having looked at NSMutableSet thats far more what I was looking for. One final question if I may:

while([mySet count] < 5) {
    NSNumber *numberToAdd = [NSNumber numberWithInt:random() %10];
    [mySet addObject:numberToAdd];
}

I don’t think it actually matters, but is it better to check if the set “containsObject” or just throw away the duplicate and carry on.

while([mySet count] < 5) {
    NSNumber *numberToAdd = [NSNumber numberWithInt:random() %10];
    if(!mySet containsObject:numberToAdd) [mySet addObject:numberToAdd];
}

Again much appreciated, thats really cool and will save me a heap of time.

gary

Answer 1

Remember an NSMutableArray is an NSArray too.

if (![theArray containsObject:theNumber]) {
  // does not contain.
}

(If you want unique objects and don’t care about insertion order, NSMutableSet is a more efficient container.)