35

スティッキー ヘッダーの作成方法に関するブログを見つけましたが、うまく機能します。唯一のことは、sectionInserts が考慮されていないと思います。

これは、その外観を意図した方法です。

ここに画像の説明を入力

私は私のインサートを持っています：

collectionViewFlowLayout.sectionInset = UIEdgeInsetsMake(16, 16, 16, 16);

スティッキー ヘッダーを使用すると、16 ピクセル分下に移動します。

ここに画像の説明を入力

元のコードをいじってみましたが、問題は最後の部分にあると思います。

layoutAttributes.frame = (CGRect){
    .origin = CGPointMake(origin.x, origin.y),
    .size = layoutAttributes.frame.size

に変更するとorigin.y - 16、ヘッダーは正しい位置で開始されますが、押し上げると、頭の 16 ピクセルが画面から消えます。

ここに画像の説明を入力

sectionInsectsを考慮に入れる方法がわかりません。誰でも助けることができますか？

ブログからの完全なコードは次のとおりです。

- (NSArray *) layoutAttributesForElementsInRect:(CGRect)rect {

    NSMutableArray *answer = [[super layoutAttributesForElementsInRect:rect] mutableCopy];
    UICollectionView * const cv = self.collectionView;
    CGPoint const contentOffset = cv.contentOffset;

    NSMutableIndexSet *missingSections = [NSMutableIndexSet indexSet];
    for (UICollectionViewLayoutAttributes *layoutAttributes in answer) {
        if (layoutAttributes.representedElementCategory == UICollectionElementCategoryCell) {
            [missingSections addIndex:layoutAttributes.indexPath.section];
        }
    }
    for (UICollectionViewLayoutAttributes *layoutAttributes in answer) {
        if ([layoutAttributes.representedElementKind isEqualToString:UICollectionElementKindSectionHeader]) {
            [missingSections removeIndex:layoutAttributes.indexPath.section];
        }
    }

    [missingSections enumerateIndexesUsingBlock:^(NSUInteger idx, BOOL *stop) {

        NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:idx];

        UICollectionViewLayoutAttributes *layoutAttributes = [self layoutAttributesForSupplementaryViewOfKind:UICollectionElementKindSectionHeader atIndexPath:indexPath];

        [answer addObject:layoutAttributes];
    }];

    for (UICollectionViewLayoutAttributes *layoutAttributes in answer) {

        if ([layoutAttributes.representedElementKind isEqualToString:UICollectionElementKindSectionHeader]) {

            NSInteger section = layoutAttributes.indexPath.section;
            NSInteger numberOfItemsInSection = [cv numberOfItemsInSection:section];

            NSIndexPath *firstCellIndexPath = [NSIndexPath indexPathForItem:0 inSection:section];
            NSIndexPath *lastCellIndexPath = [NSIndexPath indexPathForItem:MAX(0, (numberOfItemsInSection - 1)) inSection:section];

            UICollectionViewLayoutAttributes *firstCellAttrs = [self layoutAttributesForItemAtIndexPath:firstCellIndexPath];
            UICollectionViewLayoutAttributes *lastCellAttrs = [self layoutAttributesForItemAtIndexPath:lastCellIndexPath];

            CGFloat headerHeight = CGRectGetHeight(layoutAttributes.frame);
            CGPoint origin = layoutAttributes.frame.origin;
            origin.y = MIN(
                MAX(
                    contentOffset.y,
                    (CGRectGetMinY(firstCellAttrs.frame) - headerHeight)
                ),
                (CGRectGetMaxY(lastCellAttrs.frame) - headerHeight)
            );

            layoutAttributes.zIndex = 1024;
            layoutAttributes.frame = (CGRect){
                .origin = origin,
                .size = layoutAttributes.frame.size
            };
        }
    }

    return answer;
}
4

6 に答える 6

35

水平スクロールと垂直スクロールを処理し、sectionInsets を考慮するように Todd Laney が修正しました。

https://gist.github.com/evadne/4544569

@implementation StickyHeaderFlowLayout

- (NSArray *) layoutAttributesForElementsInRect:(CGRect)rect {

    NSMutableArray *answer = [[super layoutAttributesForElementsInRect:rect] mutableCopy];

    NSMutableIndexSet *missingSections = [NSMutableIndexSet indexSet];
    for (NSUInteger idx=0; idx<[answer count]; idx++) {
        UICollectionViewLayoutAttributes *layoutAttributes = answer[idx];

        if (layoutAttributes.representedElementCategory == UICollectionElementCategoryCell) {
            [missingSections addIndex:layoutAttributes.indexPath.section];  // remember that we need to layout header for this section
        }
        if ([layoutAttributes.representedElementKind isEqualToString:UICollectionElementKindSectionHeader]) {
            [answer removeObjectAtIndex:idx];  // remove layout of header done by our super, we will do it right later
            idx--;
        }
    }

    // layout all headers needed for the rect using self code
    [missingSections enumerateIndexesUsingBlock:^(NSUInteger idx, BOOL *stop) {
        NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:idx];
        UICollectionViewLayoutAttributes *layoutAttributes = [self layoutAttributesForSupplementaryViewOfKind:UICollectionElementKindSectionHeader atIndexPath:indexPath];
        if (layoutAttributes != nil) {
            [answer addObject:layoutAttributes];
        }
    }];

    return answer;
}

- (UICollectionViewLayoutAttributes *)layoutAttributesForSupplementaryViewOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath {
    UICollectionViewLayoutAttributes *attributes = [super layoutAttributesForSupplementaryViewOfKind:kind atIndexPath:indexPath];
    if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {
        UICollectionView * const cv = self.collectionView;
        CGPoint const contentOffset = cv.contentOffset;
        CGPoint nextHeaderOrigin = CGPointMake(INFINITY, INFINITY);

        if (indexPath.section+1 < [cv numberOfSections]) {
            UICollectionViewLayoutAttributes *nextHeaderAttributes = [super layoutAttributesForSupplementaryViewOfKind:kind atIndexPath:[NSIndexPath indexPathForItem:0 inSection:indexPath.section+1]];
            nextHeaderOrigin = nextHeaderAttributes.frame.origin;
        }

        CGRect frame = attributes.frame;
        if (self.scrollDirection == UICollectionViewScrollDirectionVertical) {
            frame.origin.y = MIN(MAX(contentOffset.y, frame.origin.y), nextHeaderOrigin.y - CGRectGetHeight(frame));
        }
        else { // UICollectionViewScrollDirectionHorizontal
            frame.origin.x = MIN(MAX(contentOffset.x, frame.origin.x), nextHeaderOrigin.x - CGRectGetWidth(frame));
        }
        attributes.zIndex = 1024;
        attributes.frame = frame;
    }
    return attributes;
}

- (UICollectionViewLayoutAttributes *)initialLayoutAttributesForAppearingSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath {
    UICollectionViewLayoutAttributes *attributes = [self layoutAttributesForSupplementaryViewOfKind:kind atIndexPath:indexPath];
    return attributes;
}
- (UICollectionViewLayoutAttributes *)finalLayoutAttributesForDisappearingSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath {
    UICollectionViewLayoutAttributes *attributes = [self layoutAttributesForSupplementaryViewOfKind:kind atIndexPath:indexPath];
    return attributes;
}

- (BOOL) shouldInvalidateLayoutForBoundsChange:(CGRect)newBound {
    return YES;
}

@end
于 2013-03-28T18:53:57.200 に答える
4

これは本当に良い解決策であり、完璧に機能します。ただし、shouldINvalidateLayoutForBoundsChange から YES を返す必要があるため、これは基本的にビューがスクロールするたびに prepareLayout を呼び出します。さて、prepareLayoutがレイアウト属性を作成する責任を負っている場合 (これは非常に一般的です)、これはスクロールのパフォーマンスに大きな影響を与えます。

私にとってうまくいった解決策の 1 つは、prepareLayout でレイアウト属性を作成するのではなく、invalidateLayout を呼び出す前に明示的に呼び出す別のメソッドで作成することです。UICollectionView は、レイアウトについて知る必要があると感じたときに prepareLayout を呼び出すため、このソリューションはそれらのケースにも対応します。

于 2014-05-20T12:31:13.103 に答える
2

このコードは私のために働く

    -(NSArray *)layoutAttributesForElementsInRect:(CGRect)rect {
        NSMutableArray *answer = [[super layoutAttributesForElementsInRect:rect] mutableCopy];
        UICollectionView * const cv = self.collectionView;
        //CLS_LOG(@"Number of sections = %d", [cv numberOfSections]);
        CGPoint const contentOffset = cv.contentOffset;

    //CLS_LOG(@"Adding missing sections");
    NSMutableIndexSet *missingSections = [NSMutableIndexSet indexSet];
    for (UICollectionViewLayoutAttributes *layoutAttributes in answer) {
        if (layoutAttributes.representedElementCategory == UICollectionElementCategoryCell) {
            [missingSections addIndex:layoutAttributes.indexPath.section];
        }
    }
    for (UICollectionViewLayoutAttributes *layoutAttributes in answer) {
        if ([layoutAttributes.representedElementKind isEqualToString:UICollectionElementKindSectionHeader]) {
            [missingSections removeIndex:layoutAttributes.indexPath.section];
        }
    }

    [missingSections enumerateIndexesUsingBlock:^(NSUInteger idx, BOOL *stop) {

        NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:idx];

        UICollectionViewLayoutAttributes *layoutAttributes = [self layoutAttributesForSupplementaryViewOfKind:UICollectionElementKindSectionHeader atIndexPath:indexPath];

        [answer addObject:layoutAttributes];

    }];

    NSInteger numberOfSections = [cv numberOfSections];

    //CLS_LOG(@"For loop");
    for (UICollectionViewLayoutAttributes *layoutAttributes in answer) {

        if ([layoutAttributes.representedElementKind isEqualToString:UICollectionElementKindSectionHeader]) {

            NSInteger section = layoutAttributes.indexPath.section;
            //CLS_LOG(@"Customizing layout attribute for header in section %d with number of items = %d", section, [cv numberOfItemsInSection:section]);

            if (section < numberOfSections) {
                NSInteger numberOfItemsInSection = [cv numberOfItemsInSection:section];

                NSIndexPath *firstObjectIndexPath = [NSIndexPath indexPathForItem:0 inSection:section];
                NSIndexPath *lastObjectIndexPath = [NSIndexPath indexPathForItem:MAX(0, (numberOfItemsInSection - 1)) inSection:section];

                BOOL cellsExist;
                UICollectionViewLayoutAttributes *firstObjectAttrs;
                UICollectionViewLayoutAttributes *lastObjectAttrs;

                if (numberOfItemsInSection > 0) { // use cell data if items exist
                    cellsExist = YES;
                    firstObjectAttrs = [self layoutAttributesForItemAtIndexPath:firstObjectIndexPath];
                    lastObjectAttrs = [self layoutAttributesForItemAtIndexPath:lastObjectIndexPath];
                } else { // else use the header and footer
                    cellsExist = NO;
                    firstObjectAttrs = [self layoutAttributesForSupplementaryViewOfKind:UICollectionElementKindSectionHeader
                                                                            atIndexPath:firstObjectIndexPath];
                    lastObjectAttrs = [self layoutAttributesForSupplementaryViewOfKind:UICollectionElementKindSectionFooter
                                                                           atIndexPath:lastObjectIndexPath];

                }

                CGFloat topHeaderHeight = (cellsExist) ? CGRectGetHeight(layoutAttributes.frame) : 0;
                CGFloat bottomHeaderHeight = CGRectGetHeight(layoutAttributes.frame);
                CGRect frameWithEdgeInsets = UIEdgeInsetsInsetRect(layoutAttributes.frame,
                                                                   cv.contentInset);

                CGPoint origin = frameWithEdgeInsets.origin;

                origin.y = MIN(
                               MAX(
                                   contentOffset.y + cv.contentInset.top,
                                   (CGRectGetMinY(firstObjectAttrs.frame) - topHeaderHeight)
                                   ),
                               (CGRectGetMaxY(lastObjectAttrs.frame) - bottomHeaderHeight)
                               );

                layoutAttributes.zIndex = 1024;
                layoutAttributes.frame = (CGRect){
                    .origin = origin,
                    .size = layoutAttributes.frame.size
                };
            }
        }

    }

    return answer;

}

- (BOOL) shouldInvalidateLayoutForBoundsChange:(CGRect)newBound {
    return YES;
}

この人たちを試してみてください...

于 2014-08-19T04:27:01.087 に答える
0

上記のどれも私にとってはうまくいきませんでした。私は、インセットを処理して、Photo.app スタイルのスクロール コレクションを提供するクリーンなレイアウトを探していました。

ここで提案されたソリューションを適応させて、edgeInsets 設定を処理しました。わかりやすくするために、ここに完全なソリューションを添付します。ただし、次の要点から完全なソリューションを取得できます: #3e1955a4492a897e677f。

@implementation SpringboardLayout

- (id)init
{
    if (self = [super init])
    {
        self.headerReferenceSize = CGSizeMake(0, 50);
        self.footerReferenceSize = CGSizeMake(0, 0);
        self.sectionInset = UIEdgeInsetsMake(10, 10, 80, 10);
        self.scrollDirection = UICollectionViewScrollDirectionVertical;
        self.minimumInteritemSpacing = 10;
        self.minimumLineSpacing = 10;
        if(IS_IPHONE_6 || IS_IPHONE_6PLUS) {
            self.itemSize = CGSizeMake(100, 128);
        } else {
            self.itemSize = CGSizeMake(80, 108);
        }
    }
    return self;
}

- (BOOL) shouldInvalidateLayoutForBoundsChange:(CGRect)newBound {
    return YES;
}

- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect {

    NSMutableArray *answer = [[super layoutAttributesForElementsInRect:rect] mutableCopy];
    UICollectionView * const cv = self.collectionView;
    CGPoint const contentOffset = cv.contentOffset;

    NSMutableIndexSet *missingSections = [NSMutableIndexSet indexSet];

    for (UICollectionViewLayoutAttributes *layoutAttributes in answer) {
        if (layoutAttributes.representedElementCategory == UICollectionElementCategoryCell) {
            [missingSections addIndex:layoutAttributes.indexPath.section];
        } else if ([layoutAttributes.representedElementKind isEqualToString:UICollectionElementKindSectionHeader]) {
            [missingSections removeIndex:layoutAttributes.indexPath.section];
        }
    }

    [missingSections enumerateIndexesUsingBlock:^(NSUInteger idx, BOOL *stop) {

        NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:idx];

        UICollectionViewLayoutAttributes *layoutAttributes = [self layoutAttributesForSupplementaryViewOfKind:UICollectionElementKindSectionHeader atIndexPath:indexPath];

        [answer addObject:layoutAttributes];

    }];

    for (UICollectionViewLayoutAttributes *layoutAttributes in answer) {

        if ([layoutAttributes.representedElementKind isEqualToString:UICollectionElementKindSectionHeader]) {

            NSInteger section = layoutAttributes.indexPath.section;
            NSInteger numberOfItemsInSection = [cv numberOfItemsInSection:section];

            NSIndexPath *firstObjectIndexPath = [NSIndexPath indexPathForItem:0 inSection:section];
            NSIndexPath *lastObjectIndexPath = [NSIndexPath indexPathForItem:MAX(0, (numberOfItemsInSection - 1)) inSection:section];

            BOOL cellsExist;
            UICollectionViewLayoutAttributes *firstObjectAttrs;
            UICollectionViewLayoutAttributes *lastObjectAttrs;

            if (numberOfItemsInSection > 0) { // use cell data if items exist
                cellsExist = YES;
                firstObjectAttrs = [self layoutAttributesForItemAtIndexPath:firstObjectIndexPath];
                lastObjectAttrs = [self layoutAttributesForItemAtIndexPath:lastObjectIndexPath];
            } else { // else use the header and footer
                cellsExist = NO;
                firstObjectAttrs = [self layoutAttributesForSupplementaryViewOfKind:UICollectionElementKindSectionHeader
                                                                        atIndexPath:firstObjectIndexPath];
                lastObjectAttrs = [self layoutAttributesForSupplementaryViewOfKind:UICollectionElementKindSectionFooter
                                                                       atIndexPath:lastObjectIndexPath];

            }

            CGFloat topHeaderHeight = (cellsExist) ? CGRectGetHeight(layoutAttributes.frame) : 0;
            CGFloat bottomHeaderHeight = CGRectGetHeight(layoutAttributes.frame);
            CGRect frameWithEdgeInsets = UIEdgeInsetsInsetRect(layoutAttributes.frame,
                                                               cv.contentInset);

            CGPoint origin = frameWithEdgeInsets.origin;


            origin.y = MIN(MAX(contentOffset.y + cv.contentInset.top,
                               (CGRectGetMinY(firstObjectAttrs.frame) - topHeaderHeight - self.sectionInset.top))
                           ,(CGRectGetMaxY(lastObjectAttrs.frame) - bottomHeaderHeight + self.sectionInset.bottom));
            layoutAttributes.zIndex = 1024;
            layoutAttributes.frame = (CGRect){
                .origin = origin,
                .size = layoutAttributes.frame.size
            };
        }
    }
    return answer;
}

@end
于 2015-01-17T18:16:19.963 に答える