UICollectionViewFlowLayout实现

Question

我正在努力实现以下目标，我已经用UIScrollview很容易做到了这一点，但我最近一直在尝试UICollectionView (我知道我在这个游戏中相当晚)，我很想知道为了做我想做的事情，我必须实现一个自定义布局，或者如果FlowLayout已经为我做了这件事。

基本上，如果你看一下附件，你会注意到滚动可以发生在垂直和水平两个方向，所有的行都会超过UICollectionView的高度。超出集合视图宽度的列也会发生同样的情况。

这可以用Flowlayout来实现吗？

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Answer 1

我就是这样做的。

#define space 5
#import "MultpleLineLayout.h"

@implementation MultpleLineLayout { // a subclass of UICollectionViewFlowLayout
    NSInteger itemWidth;
    NSInteger itemHeight;
}

-(id)init {
    if (self = [super init]) {
        itemWidth = 60;
        itemHeight = 60;
    }
    return self;
}

-(CGSize)collectionViewContentSize {
    NSInteger xSize = [self.collectionView numberOfItemsInSection:0] * (itemWidth + space); // "space" is for spacing between cells.
    NSInteger ySize = [self.collectionView numberOfSections] * (itemHeight + space);
    return CGSizeMake(xSize, ySize);
}

- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)path {
    UICollectionViewLayoutAttributes* attributes = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:path];
    attributes.size = CGSizeMake(itemWidth,itemHeight);
    int xValue = itemWidth/2 + path.row * (itemWidth + space);
    int yValue = itemHeight + path.section * (itemHeight + space);
    attributes.center = CGPointMake(xValue, yValue);
    return attributes;
}


-(NSArray*)layoutAttributesForElementsInRect:(CGRect)rect {
    NSInteger minRow =  (rect.origin.x > 0)?  rect.origin.x/(itemWidth + space) : 0; // need to check because bounce gives negative values  for x.
    NSInteger maxRow = rect.size.width/(itemWidth + space) + minRow;
    NSMutableArray* attributes = [NSMutableArray array];
    for(NSInteger i=0 ; i < self.collectionView.numberOfSections; i++) {
        for (NSInteger j=minRow ; j < maxRow; j++) {
            NSIndexPath* indexPath = [NSIndexPath indexPathForItem:j inSection:i];
            [attributes addObject:[self layoutAttributesForItemAtIndexPath:indexPath]];
        }
    }
    return attributes;
}

我的数据源是一个数组数组，每个内部数组提供单独行的数据。

编辑后的：

我的收藏视图在两个方向上滚动。这是我在viewDidload中设置的内容：

- (void)viewDidLoad {
    self.theData = @[@[@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"10",@"11",@"12",@"13",@"14",@"15",@"16",@"17",@"18",@"19",@"20"], @[@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"10",@"11",@"12",@"13",@"14",@"15",@"16",@"17",@"18",@"19",@"20"],@[@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"10",@"11",@"12",@"13",@"14",@"15",@"16",@"17",@"18",@"19",@"20"],@[@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"10",@"11",@"12",@"13",@"14",@"15",@"16",@"17",@"18",@"19",@"20"],@[@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"10",@"11",@"12",@"13",@"14",@"15",@"16",@"17",@"18",@"19",@"20"],@[@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"10",@"11",@"12",@"13",@"14",@"15",@"16",@"17",@"18",@"19",@"20"],@[@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"10",@"11",@"12",@"13",@"14",@"15",@"16",@"17",@"18",@"19",@"20"],@[@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"10",@"11",@"12",@"13",@"14",@"15",@"16",@"17",@"18",@"19",@"20"],@[@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"10",@"11",@"12",@"13",@"14",@"15",@"16",@"17",@"18",@"19",@"20"],@[@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"10",@"11",@"12",@"13",@"14",@"15",@"16",@"17",@"18",@"19",@"20"],@[@"Z0",@"Z1",@"Z2",@"Z3",@"Z4",@"Z5",@"Z6",@"Z7",@"Z8",@"Z9",@"Z10",@"Z11",@"Z12",@"Z13",@"Z14",@"Z15",@"Z16",@"Z17",@"Z18",@"Z19",@"Z20"]];
    MultpleLineLayout *layout = [[MultpleLineLayout alloc] init];
    self.collectionView = [[RDCollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:layout];
    self.collectionView.dataSource = self;
    self.collectionView.delegate = self;
    self.view.backgroundColor = [UIColor blackColor];
    [self.view addSubview:self.collectionView];
    [self.collectionView registerClass:[DataCell class] forCellWithReuseIdentifier:@"DataCell"];
    [self.collectionView reloadData];
}