Reproducing Popular iOS Controls - Part 9: | Ray Wenderlich Videos

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In this challenge you'll enhance the control by letting the user tap on a cell to select it.

This is a companion discussion topic for the original entry at https://www.raywenderlich.com/5298-reproducing-popular-ios-controls/lessons/9
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There is a Bug in collection view layout.
We can’t select the first and second images, It suddenly jumps to another one!

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@leamars Can you please help with this when you get a chance? Thank you - much appreciated! :]

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@leamars @shogunkaramazov
I’ve found a solution for this using UICollectionViewDelegateFlowLayout,

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
    let side = lensCollectionView.frame.height  * 2
    return UIEdgeInsets(top: 0, left: side, bottom: 0, right: side)
}

fixed it , *2 is because we the collection view end with 2 cells at start and end of it self. but scroll view can’t extend it to center!
It helps left and right of section ( we have 1 section here at all ) to have necessary margin ( here is UIEdgeInsets )

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Fantastic! Great job on figuring that out on your own :D!

Thanks for posting your solution, and apologies for not replying sooner.

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I just wanted to note that to have it perfectly centered, I used :
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets { let inset = lensCollectionView.frame.height * 0.9 * 2 + lensCollectionView.frame.height * 0.1 return UIEdgeInsets(top: 0, left: inset, bottom: 0, right: inset) }

And in LensFlowLayout, in override func prepare()method, we should call super.prepare at the end to avoid a “UICollectionViewFlowLayout undefined behavior” warning in the console.

1 Like
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Fantastic :D! Thanks for sharing!

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your solution doesn’t work properly. Still first and last items not getting centered.

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Sorry, I realized that I only tested it on iPhone X, I hope you found a better solution.

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Thanks for the solution. It fix the drag problem. However when you select the 2nd icon, it will trigger viewDidLayoutSubviews and scroll back to middle icon.

My solution is add a property to lensController to determine whether it is the first time to layout subviews. It works though I don’t know if there is a better solution to address the multiple trigger of viewDidLayoutSubviews problem.

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@bing Thank you for sharing your solution - much appreciated!