自定义UICollectionViewFlowLayout

🍓想实现以下的布局,用一个collectionView做到,需要我们自定义UICollectionViewFlowLayout来实现布局,

myCov.png

🍓首先创建一个类继承于```UICollectionViewFlowLayout`` `,详细的代码如下

#define KWIDTH [UIScreen mainScreen].bounds.size.width
#define KHEIGHT [UIScreen mainScreen].bounds.size.height
@interface CustomFlowLayout (){
    CGFloat _space;
    CGFloat _bigsizeH;
    CGFloat _smallSizeH;
    CGFloat _sizeW;
    CGFloat _cellSpace;
}

@end
@implementation CustomFlowLayout
-(CGSize)collectionViewContentSize{
//这个方法执行两次,分别在生成空白的attributes对象的前后
    _space = 5.0; //这是方块之间的间距
    _bigsizeH = 200.0; //这里是大方块的高度
    _smallSizeH = (_bigsizeH -_space)/2;  //小方块的高度
    _sizeW = (KWIDTH -_space*2)/2;  //方块的宽度
    _cellSpace = 2*(_space+_bigsizeH); 
    NSInteger num = [[self collectionView]numberOfItemsInSection:0];
    
    CGFloat height = ceil(num/3.0)*(_bigsizeH+_space*2+1);
    return CGSizeMake(KWIDTH, height);
    
}//返回contentsize的总大小

-(BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds{
    return YES;
}
- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)path{
    UICollectionViewLayoutAttributes* attributes = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:path];
    //生成空白的attributes对象，只记录了类型是cell以及对应的位置是indexPath
    //这里我是以6个方块为一组,对它们的坐标进行设置的
    CGRect rect = CGRectZero;
    NSInteger index = path.item;
    if (index%6 == 0) {
        int idx = (int)index/6;
        rect = CGRectMake(_space, idx*_cellSpace, _sizeW, _bigsizeH);
    }else if ((index-1)%6 == 0){
        int idx = (int)(index-1)/6;
        rect = CGRectMake(_space*2+_sizeW, idx*_cellSpace, _sizeW, _smallSizeH);
    }else if ((index-2)%6==0){
        int idx = (int)(index-2)/6;
        rect = CGRectMake(_space*2+_sizeW, idx*_cellSpace+(_smallSizeH+_space), _sizeW, _smallSizeH);
    }else if ((index -3)%6 == 0){
        int idx = (int)(index-3)/6;
        rect = CGRectMake(_space,idx*_cellSpace+_space+_bigsizeH ,_sizeW, _smallSizeH);
    }else if ((index-4)%6 ==0){
        int idx = (int)(index-4)/6;
        rect = CGRectMake(_space, idx*_cellSpace+2*_space+_bigsizeH+_smallSizeH, _sizeW, _smallSizeH);
    }else if ((index-5)%6==0){
        int idx = (int)(index-5)/6;
        rect = CGRectMake(_space*2+_sizeW, idx*_cellSpace+_bigsizeH+_space, _sizeW, _bigsizeH);
    }
    
    attributes.frame = rect;
    return attributes;
}
-(NSArray*)layoutAttributesForElementsInRect:(CGRect)rect{
    NSArray *array = [super layoutAttributesForElementsInRect:rect];
    NSMutableArray* attributes = [NSMutableArray array];
    for (NSInteger i=0 ; i < [array count]; i++) {
        NSIndexPath* indexPath = [NSIndexPath indexPathForItem:i inSection:0];
        [attributes addObject:[self layoutAttributesForItemAtIndexPath:indexPath]];
    }
    return attributes;
}

❤️如果需要改变布局那么就可以改变attributes对象的坐标以达到自己想要的布局效果.

以上😁