iOS UICollectionView 分页大小（UICollectionViewFlowLayout）

PagingEnableLayout.h

#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

@interface PagingEnableLayout : UICollectionViewFlowLayout

+ (CGFloat)itemWidth ;
+ (CGFloat)collectionViewWidth ;

@end

NS_ASSUME_NONNULL_END

PagingEnableLayout.m

#import "PagingEnableLayout.h"
#import <objc/message.h>

@implementation PagingEnableLayout

+ (CGFloat)itemWidth {
    return PagingEnableLayout.collectionViewWidth * 0.8;
}
+ (CGFloat)collectionViewWidth {
    return [[UIScreen mainScreen] bounds].size.width;
}

- (void)prepareLayout{
    [super prepareLayout];
    
    CGFloat contentInset = PagingEnableLayout.collectionViewWidth - PagingEnableLayout.itemWidth;
    self.collectionView.decelerationRate = UIScrollViewDecelerationRateFast;
    if ([self.collectionView respondsToSelector:NSSelectorFromString(@"_setInterpageSpacing:")]) {
        ((void(*)(id,SEL,CGSize))objc_msgSend)(self.collectionView, NSSelectorFromString(@"_setInterpageSpacing:"), CGSizeMake(-(contentInset-self.minimumLineSpacing), 0));
    }
    if ([self.collectionView respondsToSelector:NSSelectorFromString(@"_setPagingOrigin:")]) {
        ((void(*)(id,SEL,CGPoint))objc_msgSend)(self.collectionView, NSSelectorFromString(@"_setPagingOrigin:"), CGPointMake(0, 0));
    }
}

@end

改变 CGSizeMake(-(contentInset-self.minimumLineSpacing), 0) 或 CGPointMake(0, 0) 中的 x 属性改变偏移量实现更多效果。

#import "ViewController.h"
#import "PagingEnableLayout.h"

@interface ViewController () <UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout>

@property (nonatomic, strong) UICollectionView *collectionView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    [self.view addSubview:self.collectionView];
}

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    return 5;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"ID" forIndexPath:indexPath];
    cell.backgroundColor = [UIColor colorWithRed:arc4random()%256/255.0 green:arc4random()%256/255.0 blue:arc4random()%256/255.0 alpha:1];
    return cell;
}

- (UICollectionView *)collectionView {
    if (!_collectionView) {
        PagingEnableLayout *layout = [[PagingEnableLayout alloc] init];
        layout.itemSize = CGSizeMake(PagingEnableLayout.itemWidth, 500);
        layout.minimumLineSpacing = 10;
        layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
        
        _collectionView = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 200, PagingEnableLayout.collectionViewWidth, 500) collectionViewLayout:layout];
        [_collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"ID"];
        _collectionView.delegate = self;
        _collectionView.dataSource = self;
        _collectionView.backgroundColor = [UIColor whiteColor];
        _collectionView.showsHorizontalScrollIndicator = NO;
        _collectionView.pagingEnabled = YES;
    }
    return _collectionView;
}

@end

实现效果：

111.gif