Best way to find object in Array - ios

Question

I have array with arrays ex.:
(
(
object,
object
),
(
object,
object,
object,
object
)
)
Each objecthas property .objectID.What is the best way to find object with specific objectID?

Answer 1

Here are two options for you:
Option 1: using nested for loops
CustomObject *searchingObject;
// searching through the first array (which has arrays inside of it)
// Note: this will stop looping if it searched through all the objects or if it found the object it was looking for
for (int i = 0; i < [firstArray count] && searchingObject; i++) {
// accessing the custom objects inside the nested arrays
for (CustomObject *co in firstArray[i]) {
if ([co.objectId == 9235) {
// you found your object
searchingObject = co; // or do whatever you wanted to do.
// kill the inside for-loop the outside one will be killed when it evaluates your 'searchingObject'
break;
}
}
}
Option 2: using blocks:
// you need __block to write to this object inside the block
__block CustomObject *searchingObject;
// enumerating through the first array (containing arrays)
[firstArray enumerateObjectsUsingBlock:^(NSArray *nestedArray, NSUInteger indx, BOOL *firstStop) {
// enumerating through the nested array
[nestedArray enumerateObjectsUsingBlock:^(CustomObject *co, NSUInteger nestedIndx, BOOL *secondStop) {
if ([co.objectId == 28935) {
searchingObject = co; // or do whatever you wanted to do.
// you found your object now kill both the blocks
*firstStop = *secondStop = YES;
}
}];
}];
Although still considered N^2 execution time these will only run as far as they need to. Once they find the object they cease searching.

Answer 2

try it with
[ary filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:#"objectID == %#", objectID]];
--
id object = nil;
NSPredicate *pred = [NSPredicate predicateWithFormat:#"objectID == %#", objectID];
for(NSArray *subAry in ary)
{
NSArray *result = [subAry filteredArrayUsingPredicate:pred];
if(result && result.count > 0)
{
object = [result objectAtIndex:0];
break;
}
}
for Zombies cares everyone himself :P

Answer 3

If you aren't concerned with order, you could instead use an array of dictionaries where the objectId is the key. That makes your search O(N).