Question

I have an NSMutableArray called myObjectArray which contains and array of NSObjects called myObject. myObject has two fields (elements?) which are NSString‘s. like this:

@interface myObject : NSObject {
   NSString * string1;
   NSString * string2;
}

I have an NSMutableArray which contains about 50 of these objects, all with different string1’s and string2’s. then I have and independent NSString variable, called otherString;

Is there a fast way to access the myObject from myObjectArray whose string1 matches otherString?

i should say, this is what i have, but i wonder if there is a faster way:

-(void) matchString: {

    NSString * testString = otherString;
    for(int i=0; i<[myObjectArray count];i++){
    myObject * tempobject = [myObjectArray objectAtIndex:i];
        NSString * tempString = tempobject.string1;
        if ([testString isEqualToString:tempString]) {
            // do whatever
        }

    }

}

Answer 1

There are a few ways you can do this,

Using Predicates

NSPredicate * filterPredicate = [NSPredicate predicateWithFormat:@"string1 MATCHES[cd] %@", otherString];
NSArray * filteredArray = [myObjectArray filteredArrayUsingPredicate:filterPredicate];

Now filteredArray has all the myObject instances that have their string1 matching otherString.

Using indexOfObjectPassingTest:

NSUInteger index = [myObjectArray indexOfObjectPassingTest:^(BOOL)(id obj, NSUInteger idx, BOOL *stop){
    myObject anObject = obj;
    return [anObject.string1 isEqualToString:otherString];
}

If there is an object that satisfies the condition, index will point you to its index. Otherwise it will have the value NSNotFound.

You can also look at indexesOfObjectsPassingTest: if you want all the objects satisfying the condition.