Question

Okay, so, I’m doing a simple lookup. I have an array of NSString objects and a string to search for in the array’s elements.

It all seems to work up until I try to add a match to a new mutable array made to hold the search results. The stringHolder variable gets the string, and resultsCollectorArray even get the right number of new elements, but each element is empty and “out of range”. Here’s the method:

@implementation NSArray (checkForString)

-(NSMutableArray *) checkForString: (NSString *) matchSought
{
    long unsigned numberofArrayElements;
    long unsigned loop = 0;
    NSRange searchResults;
    NSMutableArray * resultCollectorArray = [[NSMutableSet alloc] init];
    id stringHolder;

    numberofArrayElements = [self count];

    while (loop < numberofArrayElements) {
        searchResults.length = 0;
        searchResults = [[self objectAtIndex: loop] rangeOfString: matchSought options:NSCaseInsensitiveSearch];
        if (searchResults.length > 0) {
            stringHolder = [self objectAtIndex: loop];
            [resultCollectorArray addObject: stringHolder];
        }
        loop++;
    }

    return [resultCollectorArray autorelease];

}

Once we get back to the main portion of the program, I get an unrecognized selector sent to the mutable array that was supposed to receive the result of the method. Here’s the main section:

#import <Foundation/Foundation.h>
#import "LookupInArray.h"

int main (int argc, const char * argv[])
{

    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    NSString *testString = [[NSString alloc] initWithString: @"ab"];
    NSMutableString * resultString = [[NSString alloc] init];
    NSArray * theArray = [[NSArray alloc] initWithObjects: ..., nil];  // Actual code has the objects
    NSMutableArray *resultArray = [[NSMutableArray alloc] init];

    NSUInteger arrayCount = 0;
    unsigned long loops = 0;


    resultArray = [theArray checkForString: testString];
    arrayCount = [resultArray count];

        while (loops < arrayCount){
            resultString = [resultArray objectAtIndex: loops];  // Here's where we get the unrecognized selector.
            NSLog(@"%@", resultString);
            loops++;
    }


    [pool drain];  // Also, I'll release the objects later. I just want to get what's above working first. 
    return 0;
}

I’ve searched the other answers (for hours now), but didn’t seen anything that solved the issue.

Any and all help would be really appreciated.

And thanks beforehand.

Answer 1

NSMutableArray * resultCollectorArray = [[NSMutableSet alloc] init]; is so incorrect. You are creating a mutable set and assigning it to a mutable array.

You are getting unrecognized selector because objectAtIndex: is not a valid selector for NSMutableSet. Make that statement,

NSMutableArray * resultCollectorArray = [[NSMutableArray alloc] init];

A Better way

NSArray * filteredArray = [array filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"SELF contains[cd] %@", searchString]];

You can directly filter the array using predicates. This way you do this in a single step. 🙂