UICollectionView iOS 9 issue on project with RTL l

问题:

It seems like Apple's new feature of auto-flip interface on RTL languages cause problems when using UICollectionView.

I used constraints of type Trailing/Leading for the collection view and they switched their values, as they should, on RTL language.

The problem is that the data actually presented is of the last indexPath in the collection's data source but the UIScrollView.contentOffset.x of the first cell is 0.

A proper behaviour would have been one of the following:

1. Displaying the first indexPath correctly and switching the direction of the scroll (to the right) - Best option
2. Not flipping the UI/Constraints so the presented-data / indexPath / scrollView.contentOffset.x will be synchronised - Option that disabling the RTL support.
3. Presenting cell and data of the last indexPath but fixing the scrollView.contentOffset.x to represent the last cell position also.

I guess Apple might fix it sometime in the future but meanwhile we'll have to use workarounds like reversing array and/or scrolling to the last object.

回答1:

I was in a similar situation and found a solution for this. If you are using swift, add the following snippet to your project, and it will make sure that the bounds.origin always follows leading edge of the collection view.

extension UICollectionViewFlowLayout {

    open override var flipsHorizontallyInOppositeLayoutDirection: Bool {
        return true
    }
}

If you are using Objective-C, just subclass the UICollectionViewLayout class, and override flipsHorizontallyInOppositeLayoutDirection, and return true. Use this subclass as the layout object of your collection view.

回答2:

There is one common solution for that problem that works for me, follow below steps to overcome that problem,

• Give the auto layout constraint as per your requirement and then from attribute inspector change the semantic control property of the collection view to Force right-to-left from the storyboard.

• Then open storyboard as source code and find for the “leading” attributes of your relevant collection view and replace that with the “left” and same for the “trailing” replace that with the “right”. Now you almost done.

• now that will give you result as per your requirement.

回答3:

import UIKit

extension UICollectionViewFlowLayout {

    open override var flipsHorizontallyInOppositeLayoutDirection: Bool {
        return UIApplication.shared.userInterfaceLayoutDirection == UIUserInterfaceLayoutDirection.rightToLeft
    }