iOS-UICollectionViewLayout 自定义布局

Model cell

#import <UIKit/UIKit.h>
@interface ImageCell : UICollectionViewCell
@property (nonatomic, copy) NSString *image;
@end

#import "ImageCell.h"

@interface ImageCell()
@property (weak, nonatomic) IBOutlet UIImageView *imageView;
@end

@implementation ImageCell
- (void)awakeFromNib {
    self.imageView.layer.borderWidth = 3;
    self.imageView.layer.borderColor = [UIColor whiteColor].CGColor;
    self.imageView.layer.cornerRadius = 3;
    self.imageView.clipsToBounds = YES;
}

- (void)setImage:(NSString *)image
{
    _image = [image copy];

    self.imageView.image = [UIImage imageNamed:image];
}
@end

控制器 ViewController

#import "ViewController.h"
#import "ImageCell.h"
#import "LineLayout.h"

@interface ViewController () <UICollectionViewDataSource, UICollectionViewDelegate>
@property (nonatomic, strong) NSMutableArray *images;
@property (nonatomic, weak) UICollectionView *collectionView;
@end

@implementation ViewController

static NSString *const ID = @"image";

- (NSMutableArray *)images
{
    if (!_images) {
        self.images = [[NSMutableArray alloc] init];

        for (int i = 1; i<=20; i++) {
            [self.images addObject:[NSString stringWithFormat:@"%d", i]];
        }
    }
    return _images;
}

- (void)viewDidLoad {
    [super viewDidLoad];

    CGFloat w = self.view.frame.size.height;
    CGRect rect = CGRectMake(0, 0, w, 200);
    UICollectionView *collectionView = [[UICollectionView alloc] initWithFrame:rect collectionViewLayout:[[LineLayout alloc] init]];
    collectionView.dataSource = self;
    collectionView.delegate = self;
    [collectionView registerNib:[UINib nibWithNibName:@"ImageCell" bundle:nil] forCellWithReuseIdentifier:ID];
    [self.view addSubview:collectionView];
    self.collectionView = collectionView;
    // collectionViewLayout :
    // UICollectionViewLayout
    // UICollectionViewFlowLayout
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    if ([self.collectionView.collectionViewLayout isKindOfClass:[LineLayout class]]) {
        [self.collectionView setCollectionViewLayout:[[UICollectionViewFlowLayout alloc] init] animated:YES];
    } else {
        [self.collectionView setCollectionViewLayout:[[LineLayout alloc] init] animated:YES];
    }
}

#pragma mark - <UICollectionViewDataSource>
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return self.images.count;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    ImageCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:ID forIndexPath:indexPath];
    cell.image = self.images[indexPath.item];
    return cell;
}

- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
    // 删除模型数据
    [self.images removeObjectAtIndex:indexPath.item];

    // 删UI(刷新UI)
    [collectionView deleteItemsAtIndexPaths:@[indexPath]];
}

@end

堆布局 StackLayout

#define Random0_1 (arc4random_uniform(100)/100.0)

#import "StackLayout.h"

@implementation StackLayout

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

//- (CGSize)collectionViewContentSize
//{
// return CGSizeMake(500, 500);
//}

- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath
{
    NSArray *angles = @[@0, @(-0.2), @(-0.5), @(0.2), @(0.5)];
    UICollectionViewLayoutAttributes *attrs = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath];
    attrs.size = CGSizeMake(100, 100);
    attrs.center = CGPointMake(self.collectionView.frame.size.width * 0.5, self.collectionView.frame.size.height * 0.5);
    if (indexPath.item >= 5) {
        attrs.hidden = YES;
    } else {
        attrs.transform = CGAffineTransformMakeRotation([angles[indexPath.item] floatValue]);
        // zIndex越大,就越在上面
        attrs.zIndex = [self.collectionView numberOfItemsInSection:indexPath.section] - indexPath.item;
    }
    return attrs;
}

- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect
{
    NSMutableArray *array = [NSMutableArray array];
    NSInteger count = [self.collectionView numberOfItemsInSection:0];
    for (int i = 0; i<count; i++) {
        UICollectionViewLayoutAttributes *attrs = [self layoutAttributesForItemAtIndexPath:[NSIndexPath indexPathForItem:i inSection:0]];
        [array addObject:attrs];
    }
    return array;
}

@end

圆形布局 CircleLayout

#import "CircleLayout.h"

@implementation CircleLayout
- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds
{
    return YES;
}

- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath
{
    UICollectionViewLayoutAttributes *attrs = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath];

    attrs.size = CGSizeMake(50, 50);

    // 圆的半径
    CGFloat circleRadius = 70;
    CGPoint circleCenter = CGPointMake(self.collectionView.frame.size.width * 0.5, self.collectionView.frame.size.height * 0.5);
    // 每个item之间的角度
    CGFloat angleDelta = M_PI * 2 / [self.collectionView numberOfItemsInSection:indexPath.section];

    // 计算当前item的角度
    CGFloat angle = indexPath.item * angleDelta;

    attrs.center = CGPointMake(circleCenter.x + circleRadius * cosf(angle), circleCenter.y - circleRadius * sinf(angle));

    attrs.zIndex = indexPath.item;

    return attrs;
}

- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect
{
    NSMutableArray *array = [NSMutableArray array];
    NSInteger count = [self.collectionView numberOfItemsInSection:0];
    for (int i = 0; i<count; i++) {
        UICollectionViewLayoutAttributes *attrs = [self layoutAttributesForItemAtIndexPath:[NSIndexPath indexPathForItem:i inSection:0]];
        [array addObject:attrs];
    }
    return array;
}
@end