Inserting Objects into NSMutableArray

Question

Currently, I have edited a delegate function that adds Exercise objects to an NSMutableArray. However, I would not like to add duplicate objects, instead, if the object is already in the array, i'd like to simply access that particular object.

Here is my code:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

    UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
    NSString *str = cell.textLabel.text; // Retrieves the string of the selected cell.

    Exercise *exerciseView = [[Exercise alloc] initWithExerciseName:str];
    WorkoutManager *workoutManager = [WorkoutManager sharedInstance];

    if (![[workoutManager exercises] containsObject:exerciseView]) {
        [[workoutManager exercises] insertObject:exerciseView atIndex:0];
        [self presentModalViewController:exerciseView animated:YES];
        NSLog(@"%@", [workoutManager exercises]); 
    }
    else {
        [self presentModalViewController:exerciseView animated:YES];
        NSLog(@"%@", [workoutManager exercises]); 
    }
}

I thought this would work, however, when I ran my code and NSLogged my array, it showed that when I clicked on the same cell, two seperate objects were created. Any help?

jonkroll · Accepted Answer · 2012-04-25 03:05:02Z

3

Each time you call

Exercise *exerciseView = [[Exercise alloc] initWithExerciseName:str];

it create a new (distinct) exerciseView object. So even though the exercise name may be the same as the name for an exercise object in your exercises list, it is a brand new object so when you call containsObject the result will always be false and your new object will be added to the array.

Perhaps you should store a list of the NSString exerciseName in your workout manager instead?

answered Apr 25, 2012 at 3:05

jonkroll

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Comments

jerrylroberts · Accepted Answer · 2012-04-25 03:17:39Z

I would say this is your culprit:

Exercise *exerciseView = [[Exercise alloc] initWithExerciseName:str];

You're creating a new object each time so technically, it's not in the array. The containsObject method is just iterating through the array and calling isEqual on each object. I haven't tested this but theoretically, in your custom Exercise object, you could override the isEqual method to compare the exercise name properties and return true if they match. See, EVERYTHING has to match up when you are using containsObject so even if all the properties are the same, the objectid is not.

Easy fix without having to see your Exercise implementation:

Exercise *exerciseView = nil;

For(Exercise *exercise in [[WorkoutManager sharedInstance] exercises]){
    if(exercise.exerciseName == str) {
        exerciseView = exercise;
        break;
    }
}

if(exerciseView == nil) {
    exerciseView = [[Exercise alloc] initWithExerciseName:str];
    [[workoutManager exercises] insertObject:exerciseView atIndex:0];
}

[self presentModalViewController:exerciseView animated:YES];

Hope this helps explain WHY its happening. I didn't test this code since there are some missing pieces but you should get the idea. Have fun!

Nitin · Accepted Answer · 2012-04-25 03:29:03Z

0

WorkoutManager *workoutManager = [WorkoutManager sharedInstance];

Exercise *temp = [[Exercise alloc] initWithExerciseName:str];
for(id temp1 in workoutManager)
{
    if( [temp isKindOfClass:[Exercise class]])
    {
        NSLog(@"YES");
        // You Can Access your same object here if array has already same object
    }
}

 [temp release];
 [workoutManager release];

Hope, this will help you....

answered Apr 25, 2012 at 3:29

Nitin

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