Any way to detect index when scrolling (left<->right ) from viewcontroller ? about yzcenterflowlayout HOT 10 CLOSED

Hello @jams032

Here your queries feedback. I hope this helps you. Please let me know if any issue.

1. centerFlowLayout.currentCenteredIndexPath to get currently selected indexpath
2. centerFlowLayout.currentCenteredPage to get current selected page

from yzcenterflowlayout.

@jams032 you can do 2 way based on your requirement

1. If you continue to track which current(center) indexPath then use scroll view did scroll delegate method. This method continues to called when you scroll left or right.

// any offset changes on called
func scrollViewDidScroll(_ scrollView: UIScrollView) {
        if let indexPath = centerFlowLayout.currentCenteredIndexPath {
            print("Current indexPath: \(indexPath)")
        }
    }

2. After scrolling end with left or right then you can use the scroll view did end decelerating delegate method. This method not a continuous called on scrolling left or right.

// called when scroll view grinds to a halt
func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
        if let indexPath = centerFlowLayout.currentCenteredIndexPath {
            print("Current indexPath: \(indexPath)")
        }
    }

from yzcenterflowlayout.

@jams032 you can use scrollToPage(atIndex index: Int, animated: Bool = true) method to scroll a specific index. I hope this helps you. Please let me know if any issue.

let index =  array.count/2
collectionView.performBatchUpdates(nil) { [weak self] (isLoded) in
            guard let weakSelf = self, isLoded else { return}
            weakSelf.centerFlowLayout.scrollToPage(atIndex: index, animated: true)
 }

from yzcenterflowlayout.

@sandeep-yudiz Say, i am in the viewcontroller class now. From where i can called this ? Any place to call it in viewcontroller class when user is scrolling the collectionview ?

from yzcenterflowlayout.

@sandeep-yudiz, applying the code in viewcontroller, i got the changed index after scroll finish :

func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
    if let cIndexPath = centerFlowLayout.currentCenteredIndexPath {
        print("\(cIndexPath)")
    }
}

Do you think this is the only correct way ?

from yzcenterflowlayout.

@sandeep-yudiz yeah, i got it. Thank you so much for nice reply. I prefer using scrollViewDidEndDecelerating method because it is called at the end. scrollViewDidScroll is called so many times while scrolling, so i should not update UI so many times. Another query to you:

In the first load, we just load the collectionview with array elements. It set first item in the center. How i can set another index(may be middle item, index will be array.count/2) manually in the first load. Viewing the items from both sided will look nice in the first on viewcontroller, that's why i want to do it. Any way to set middle item in the first load ?

Thank you again.

from yzcenterflowlayout.

@sandeep-yudiz , i found this from the implementation.
You are awesome, thanks for your support.

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@jams032
Most welcome!

from yzcenterflowlayout.

@sandeep-yudiz , any shortcut to do this ? Can we show multiple side item ?

from yzcenterflowlayout.

@jams032 sorry, not possible with the current code structure for following UI.

.

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