ios - 圆形 Collection View 布局

Question

我正在尝试制作一个圆形的 Collection View 。

不知何故，我设法获得了循环 View ，但仍坚持滚动。我的 Collection View 单元格和布局是圆形的，但我无法使单元格可滚动。

`#import "CircleLayout.h"

#define ITEM_SIZE 70

@interface CircleLayout()

// arrays to keep track of insert, delete index paths
@property (nonatomic, strong) NSMutableArray *deleteIndexPaths;
@property (nonatomic, strong) NSMutableArray *insertIndexPaths;

@end

@implementation CircleLayout
-(void)awakeFromNib{
    self.scrollDirection = UICollectionViewScrollDirectionHorizontal;

}
-(id)init
{
    if (!(self = [super init])) return nil;
    self.itemSize = CGSizeMake(60.0, 200.0);
    self.sectionInset = UIEdgeInsetsMake(0, 60, 0, 60);
    self.scrollDirection = UICollectionViewScrollDirectionHorizontal;
    return self;
}
- (id)initWithCoder:(NSCoder *)aDecoder {
    self = [super initWithCoder:aDecoder];
    if (self) {
        self.itemSize = CGSizeMake(60.0, 200.0);
        self.sectionInset = UIEdgeInsetsMake(0, 60, 0, 60);
        self.scrollDirection = UICollectionViewScrollDirectionHorizontal;
    }
    return self;
}

-(void)prepareLayout
{
    [super prepareLayout];

    CGSize size = self.collectionView.frame.size;
    _cellCount = [[self collectionView] numberOfItemsInSection:0];
    _center = CGPointMake(size.width, size.height);
    _radius = MIN(size.width, size.height)/1.3f;

}

-(CGSize)collectionViewContentSize
{
    return [self collectionView].frame.size;
}

- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)path
{
    UICollectionViewLayoutAttributes* attributes = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:path];
    attributes.size = CGSizeMake(ITEM_SIZE, ITEM_SIZE);
    attributes.center = CGPointMake(_center.x + _radius * cosf(2 * path.item * M_PI / _cellCount),
                                    _center.y + _radius * sinf(2 * path.item * M_PI / _cellCount));
    return attributes;
}

-(NSArray*)layoutAttributesForElementsInRect:(CGRect)rect
{
    NSMutableArray* attributes = [NSMutableArray array];
    for (NSInteger i=0 ; i < self.cellCount; i++) {
        NSIndexPath* indexPath = [NSIndexPath indexPathForItem:i inSection:0];
        [attributes addObject:[self layoutAttributesForItemAtIndexPath:indexPath]];
    }
    return attributes;
}



- (void)prepareForCollectionViewUpdates:(NSArray *)updateItems
{
    // Keep track of insert and delete index paths
    [super prepareForCollectionViewUpdates:updateItems];

    self.deleteIndexPaths = [NSMutableArray array];
    self.insertIndexPaths = [NSMutableArray array];

    for (UICollectionViewUpdateItem *update in updateItems)
    {
        if (update.updateAction == UICollectionUpdateActionDelete)
        {
            [self.deleteIndexPaths addObject:update.indexPathBeforeUpdate];
        }
        else if (update.updateAction == UICollectionUpdateActionInsert)
        {
            [self.insertIndexPaths addObject:update.indexPathAfterUpdate];
        }
    }
}

- (void)finalizeCollectionViewUpdates
{
    [super finalizeCollectionViewUpdates];
    // release the insert and delete index paths
    self.deleteIndexPaths = nil;
    self.insertIndexPaths = nil;
}

// Note: name of method changed
// Also this gets called for all visible cells (not just the inserted ones) and
// even gets called when deleting cells!
- (UICollectionViewLayoutAttributes *)initialLayoutAttributesForAppearingItemAtIndexPath:(NSIndexPath *)itemIndexPath
{
    // Must call super
    UICollectionViewLayoutAttributes *attributes = [super initialLayoutAttributesForAppearingItemAtIndexPath:itemIndexPath];

    if ([self.insertIndexPaths containsObject:itemIndexPath])
    {
        // only change attributes on inserted cells
        if (!attributes)
            attributes = [self layoutAttributesForItemAtIndexPath:itemIndexPath];

        // Configure attributes ...
        attributes.alpha = 0.0;
        attributes.center = CGPointMake(_center.x, _center.y);
    }

    return attributes;
}

// Note: name of method changed
// Also this gets called for all visible cells (not just the deleted ones) and
// even gets called when inserting cells!
- (UICollectionViewLayoutAttributes *)finalLayoutAttributesForDisappearingItemAtIndexPath:(NSIndexPath *)itemIndexPath
{
    // So far, calling super hasn't been strictly necessary here, but leaving it in
    // for good measure
    UICollectionViewLayoutAttributes *attributes = [super finalLayoutAttributesForDisappearingItemAtIndexPath:itemIndexPath];

    if ([self.deleteIndexPaths containsObject:itemIndexPath])
    {
        // only change attributes on deleted cells
        if (!attributes)
            attributes = [self layoutAttributesForItemAtIndexPath:itemIndexPath];

        // Configure attributes ...
        attributes.alpha = 0.0;
        attributes.center = CGPointMake(_center.x, _center.y);
        attributes.transform3D = CATransform3DMakeScale(0.1, 0.1, 1.0);
    }

    return attributes;
}
- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds {
    return YES;
}
@end

`

Answer 1

我开发了一个自定义的 UICollectionviewLayout，它以圆形布局布置 Collection View 单元格。它可以配置为显示特定内容。

在你的情况下，你需要一个 180 - 90 度的中心右下角。

https://github.com/DoddaSrinivasan/DSCircularCollectionView