Question

If you wanna see the code Im having problem with, here is the link:
Code

My question is connected with my past question.

I’m really having problem with my NSMutableArray, I’m currently using iCarousel for my slotMachine object(slot1 and slot2). My app works this way:

From PhotoViewController I made a view that has thumbnail images, then assign its frame with button. So if 1 image was pressed, it will save that integer via NSUserDefaults.
Then I will retrieve it in my carouselViewController

Im thinking of adjusting the array but I can’t.
I also have tried my question here:
Comparing with NSMutableArray
If only I can do it the same as Array 2 it would be much easy, but still not working.

(ADDITIONAL INFO🙂

I have done it this way, have a Viewcontroller that contains the UIImageView with a button in it, so when the user taps it, my CustomPicker pops up. My CustomPicker contains the image on what the user have picked on the camera roll. So each button has a specific value sent to my iCarouselView using NSUserDefaults. carousel1 for First slot and carousel2 for Second slot.

Here is what I wanna do: I want to forcefully make it stop to the index the user picks. (Which Im doing in my carouselDidEndScrollingAnimtaion)

In my carouselDidEndScrollingAnimation method i tested all of my condition(individually) it works perfectly in terms of comparing.
Then when I combine the conditions, the first Two comparison or STOP is RIGHT, but the next two are always wrong. Or sometimes Got mixed up.

I need to scroll the two specific indexes/integer which was User Picked( I already done that) was able to scroll 2 pairs of them but then the next two were always wrong because I think there indexes were adjusting.

PICTURES:

Image Below is my PhotoViewController which contained the Comparing Stage SETTING of my game.UIImageVIew with UIButton.Image that will be put in the number according to it will be Forcefully and should be forcefully shown.

When my iCarousel start then it stops for example in the image below(Which is not the same as the above):

Will be forcefully scroll to the inputted image in the PhotoViewController

Into:

Summary:
Its like this. I have a settingsView from there, I will import my images(Multiple) for Slot1 & Slot2.
Then in another View the PhotoViewController that is where the image above is shown. THe first column corresponds to 1st slot followed by the 2nd slot. if a view is pressed (for example No. 1 of Slot 1 it will load a thumbnail of images loading the images picked from Picker for the Slot 1.

You will have to do it 4 times(pair) —-> The displayed here I get their indexes via NSUserDefaults via button.tag then send to iCarouselView.

Then when you are done (pressed Done button) it will go to iCarouselView then, as shown above thats the view of it.
When pressed it will spin for couple of seconds, then when finished but not stop at the user picked in the PhotoView it will forcefully scroll to that index.

QUESTION:

Is there a way to make my array or my iCarousel.view not adjust their indexes when Im deleting. To still retain my indexes the right way. Or are there other solution like adjusting my array, the same as adjusting my PhotoViewController picked indexes too. Because I think that when my array retain their indexes even deleting I would be able to solve this problem. But still can’t.

Hope you understand my question.

Answer 1

Is there a way to make my array or my iCarousel.view not adjust their indexes when Im deleting. To still retain my indexes the right way. Or are there other solution like adjusting my array, the same as adjusting my PhotoViewController picked indexes too. Because I think that when my array retain their indexes even deleting I would be able to solve this problem. But still can’t.

The only way you have to modify the way iCarousel manages its indexes is by modifying the code. Indeed, if you look at the removeViewAtIndex method in iCarousel.m, you will see that indexes are managed through an NSDictionary, and at the moment of deleting, the dictionary is rearranged (items are reordered). You could take that method:

- (void)removeViewAtIndex:(NSInteger)index
{
    NSMutableDictionary *newItemViews = [NSMutableDictionary dictionaryWithCapacity:[itemViews count] - 1];
    for (NSNumber *number in [self indexesForVisibleItems])
    {
        NSInteger i = [number integerValue];
        if (i < index)
        {
            [newItemViews setObject:[itemViews objectForKey:number] forKey:number];
        }
        else if (i > index)
        {
            [newItemViews setObject:[itemViews objectForKey:number] forKey:[NSNumber numberWithInteger:i - 1]];
        }
    }
    self.itemViews = newItemViews;
}

You could apply the same logic to your array, so that the carousel and your array keep in sync. Of course, if you store the indexes somewhere (slot1/slot2/slot2/slot4?), you should also update their values after removing an element.

On the other hand, I think that what you are asking here is how to do something that you believe would solve the problem you have, but you are not really explaining what the problem is. Indeed, if I understand you correctly, what you do is:

1. spinning the carousel;

2. when the carousel stops, if it is not by chance on the desired item, you “force” it to scroll to that item.

There is no reason why this should not work after deleting some elements (unless iCarousel has some bugs, then the solution would be catching the bug). The only part is knowing which index is the one you would like to move to.

As a suggestion, I would start off by simplifying your delegate carouselDidEndScrollingAnimation method. Indeed, your carouselDidEndScrollingAnimation has a parameter called carousel, well, I think this is the only carousel you should ever be referring to in that method. If you don’t see it, this is the reasoning: each of your carousel will stop scrolling and the carouselDidEndScrollingAnimation will be called; so that method will be called twice. Each time that method is executed you will modify the state of both carousel1 and carousel2 (by calling scrollToItemAtIndex); therefore, on each carousel you will call scrollToItemAtIndex twice.

This does no sound very correct to me. So you should find a way to scroll only carousel1 when carouselDidEndScrollingAnimation is called for carousel1 and to scroll only carousel2 when carouselDidEndScrollingAnimation is called for carousel2.

More generally, another point I would like to raise is that the idea of:

1. letting a carousel stop;

2. scrolling it again so that it reaches the desired position;

does not seem the best implementation possible since the user would see the carousel stopping and then starting over again.

The way I would approach this is by modifying directly iCarousel implementation so that it supports this specific behavior you need.

Concretely, give a look at the step method in iCarousel.m. This is called at each frame to produce the carousel animation. Now, in this method there is decelerating branch:

else if (decelerating)
{
    CGFloat time = fminf(scrollDuration, currentTime - startTime);
    CGFloat acceleration = -startVelocity/scrollDuration;
    CGFloat distance = startVelocity * time + 0.5f * acceleration * powf(time, 2.0f);
    scrollOffset = startOffset + distance;

    [self didScroll];
    if (time == (CGFloat)scrollDuration)
    {
        decelerating = NO;
        if ([delegate respondsToSelector:@selector(carouselDidEndDecelerating:)])
        {
            [delegate carouselDidEndDecelerating:self];
        }
        if (scrollToItemBoundary || (scrollOffset - [self clampedOffset:scrollOffset]) != 0.0f)
        {
            if (fabsf(scrollOffset/itemWidth - self.currentItemIndex) < 0.01f)
            {
                //call scroll to trigger events for legacy support reasons
                //even though technically we don't need to scroll at all
                [self scrollToItemAtIndex:self.currentItemIndex duration:0.01];
            }
            else
            {
                [self scrollToItemAtIndex:self.currentItemIndex animated:YES];
            }
        }
        else
        {
            CGFloat difference = (CGFloat)self.currentItemIndex - scrollOffset/itemWidth;
            if (difference > 0.5)
            {
                difference = difference - 1.0f;
            }
            else if (difference < -0.5)
            {
                difference = 1.0 + difference;
            }
            toggleTime = currentTime - MAX_TOGGLE_DURATION * fabsf(difference);
            toggle = fmaxf(-1.0f, fminf(1.0f, -difference));
        }
    }
}

and you see that when the carousel stops decelerating, it is scrolled again. This is exactly the same as you are doing, so you might find a way to modify this code and have the carousel scrolls exactly to the index you need. In this way you would get a far smoother spinning of the carousel.

Hope this helps and apologies for the lengthy reply.