UICollectionView 不会在 RTL 中从右到左填充数据

Question

我有一个 UICollectionView 并且想要水平显示单元格，例如

英文，应该显示： |细胞A |细胞B | cellC |

在阿拉伯语中，它应该显示： [细胞B |细胞A |

对于 RTL，如果每个单元格具有相同的大小，UICollectionViewFlowLayout 默认情况下对我来说工作正常。但是，如果我实现 collectionView:layout:sizeForItemAtIndexPath: 并为每个单元格设置不同的宽度，则 CollectionView 变为：

|细胞A |细胞B |细胞 C |

有什么办法可以解决这个问题吗？

Answer 1

这个 class 对我有用，可以使用不同大小的单元格从左到右显示集合视图。

#import <UIKit/UIKit.h>
#import <objc/runtime.h>

static const char kBundleKey = 0;

@interface BundleEx : NSBundle

@end

@implementation BundleEx

- (NSString *)localizedStringForKey:(NSString *)key value:(NSString *)value table:(NSString *)tableName
{
    NSBundle *bundle = objc_getAssociatedObject(self, &kBundleKey);
    if (bundle) {
        return [bundle localizedStringForKey:key value:value table:tableName];
    }
    else {
        return [super localizedStringForKey:key value:value table:tableName];
    }
}

@end

@implementation NSBundle (Language)

+ (void)setLanguage:(NSString *)language
{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        object_setClass([NSBundle mainBundle], [BundleEx class]);
    });
    if (isCurrentLanguageRTL) {
        if ([[[UIView alloc] init] respondsToSelector:@selector(setSemanticContentAttribute:)]) {
            [[UIView appearance] setSemanticContentAttribute:UISemanticContentAttributeForceRightToLeft];
            [[UITableView appearance] setSemanticContentAttribute:UISemanticContentAttributeForceRightToLeft];
        }
    }else {
        //FOR LTR
        if ([[[UIView alloc] init] respondsToSelector:@selector(setSemanticContentAttribute:)]) {
            [[UIView appearance] setSemanticContentAttribute:UISemanticContentAttributeForceLeftToRight];
            [[UITableView appearance] setSemanticContentAttribute:UISemanticContentAttributeForceLeftToRight];
        }
    }
    [[NSUserDefaults standardUserDefaults] synchronize];

    id value = language ? [NSBundle bundleWithPath:[[NSBundle mainBundle] pathForResource:language ofType:@"lproj"]] : nil;
    objc_setAssociatedObject([NSBundle mainBundle], &kBundleKey, value, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

@end

希望对您有所帮助。如果需要进一步的帮助，请告诉我。

Answer 2

您需要创建自己的 UICollectionViewLayout，正如我在评论中所说，我们将从倒着开始，首先您需要在 ViewController viewDidLoad 方法中添加此行

let semanticLayout = SemanticLayout()
semanticLayout.delegate = self
self.collectionView.collectionViewLayout = semanticLayout

这是您需要实现的委托

extension ViewController: SemanticLayoutDelegate{
    func semanticDisposition() -> SemanticDisposition {
        return SemanticDisposition.rigthToLeft
    }   
}

使用您的 ViewController 姓名代替 ViewController ofc

这里有 SemanticLayout class，检查是否 完全可定制 您可以定义 UICollectionView 是 RTL 还是具有委托方法的 LTR semanticDisposition

import UIKit


protocol SemanticLayoutDelegate: UICollectionViewDelegateFlowLayout {
    func semanticDisposition() -> SemanticDisposition
}

enum SemanticDisposition {
    case leftToRigth
    case rigthToLeft
}

class SemanticLayout: UICollectionViewLayout {

    weak var delegate: SemanticLayoutDelegate!

    fileprivate var cellPadding: CGFloat = 10

    fileprivate var cache = [UICollectionViewLayoutAttributes]()

    fileprivate var contentHeight: CGFloat = 0
    private var rowsWidth : [CGFloat] = [0]
    private var avaiableSpaces : [(Int,CGFloat)] = []
    private var currentRow : Int = 0
    private var rowHeigths : CGFloat = -1.0

    fileprivate var contentWidth: CGFloat {
        guard let collectionView = collectionView else {
            return 0
        }
        let insets = collectionView.contentInset
        return collectionView.bounds.width - (insets.left + insets.right)
    }

    private func availableWidthForRow(index:Int) -> CGFloat {
        let ocuppedWidth = self.rowsWidth[index]
        return self.contentWidth - ocuppedWidth
    }

    private func canAddCellAtRow(rowIndex:Int,size:CGSize) ->Bool
    {
        if(availableWidthForRow(index: rowIndex) >= size.width) {
            return true
        }

        return false
    }

    override var collectionViewContentSize: CGSize {
        return CGSize(width: contentWidth, height: contentHeight)
    }

    override func prepare() {
        // Check if cache is empty
        guard cache.isEmpty == true, let collectionView = collectionView else {
            return
        }

        for item in 0 ..< collectionView.numberOfItems(inSection: 0) {

            let indexPath = IndexPath(item: item, section: 0)

            let viewSize: CGSize = delegate.collectionView!(collectionView, layout: self, sizeForItemAt: indexPath)
            if(self.rowHeigths < 0) {
                self.rowHeigths = viewSize.height
            }

            let width = viewSize.width
            let height = viewSize.height

            var xOffset = self.rowsWidth[self.currentRow]
            if(self.canAddCellAtRow(rowIndex: self.currentRow, size: viewSize)) {

                if(self.delegate.semanticDisposition() == .rigthToLeft) {
                    xOffset = (contentWidth - self.rowsWidth[self.currentRow]) - width
                }

            } else {
                self.currentRow += 1
                self.rowsWidth.append(0.0)
                xOffset = self.rowsWidth[self.currentRow]
                if(self.delegate.semanticDisposition() == .rigthToLeft) {
                    xOffset = (contentWidth - self.rowsWidth[self.currentRow]) - width
                }

            }

            let yOffset = CGFloat(self.currentRow) * self.rowHeigths

            let frame = CGRect(x: xOffset, y: yOffset, width: width, height: height)
            let insetFrame = frame.insetBy(dx: cellPadding, dy: cellPadding)

            let attributes = UICollectionViewLayoutAttributes(forCellWith: indexPath)
            attributes.frame = insetFrame
            cache.append(attributes)

            contentHeight = max(contentHeight, frame.maxY)

            self.rowsWidth[self.currentRow]  += width
        }
    }

    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {

        var visibleLayoutAttributes = [UICollectionViewLayoutAttributes]()

        // Loop through the cache and look for items in the rect
        for attributes in cache {
            if attributes.frame.intersects(rect) {
                visibleLayoutAttributes.append(attributes)
            }
        }
        return visibleLayoutAttributes
    }

    override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
        return cache[indexPath.item]
    }
}

结果 RTL

LTR

Answer 3

class RTLSupportedCollectionViewFlowLayout: UICollectionViewFlowLayout {

    override var flipsHorizontallyInOppositeLayoutDirection: Bool {
        return true
    }
}

您可以使用这种流式布局。仅当所有单元格返回的项目大小不同时才需要它。

UICollectionView 不会在 RTL 中从右到左填充数据

UICollectionView doesn't fill data from right to left in RTL

ios

right-to-left

collectionview