Question

我有一个UICollectionView，想水平显示单元格，例如

英语，它应显示： | cellA | cellB | cellC |

阿拉伯语，它应显示： [cellC | cellB | cellA |

对于RTL，如果每个单元格的大小相同，默认情况下UICollectionViewFlowLayout可以正常工作。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：

| cellA | cellB | cellC |

有什么办法可以解决这个问题？

Answer 1

您需要创建自己的UICollectionViewLayout，正如我在评论中所说，我们将倒退，首先需要在ViewController viewDidLoad方法上添加以下行

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名称而不是c的ViewController

这里有SemanticLayout类，请检查可完全自定义，您可以使用委托方法UICollectionView定义semanticDisposition是RTL还是LTR

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 2

class RTLSupportedCollectionViewFlowLayout: UICollectionViewFlowLayout {

    override var flipsHorizontallyInOppositeLayoutDirection: Bool {
        return true
    }
}

您可以使用此流布局。仅当返回的项目大小对于所有单元格都不相同时才需要。

Answer 3

该课程对我来说非常有用，可以从左到右显示不同大小的单元格的集合视图。

#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

希望此帮助。让我知道是否需要进一步的帮助。

Answer 4

首先，当创建UICollectionView时，我对其进行了水平翻转：

collectionView.transform = CGAffineTransform(scaleX: -1, y: 1)

然后子类UICollectionViewCell并在此处对其contentView进行相同的水平翻转：

contentView.transform = CGAffineTransform(scaleX: -1, y: 1)

注意：如果您的单元格中有任何子视图，则也要对其进行转换。例如cell.lblTitle.transform = CGAffineTransform（scaleX：-1，y：1）

UICollectionView不会在RTL中从右向左填充数据

4 个答案: