我假设您使用的是默认的UICollectionViewDelegateFlowLayout，对吗？然后确保您对代理方法做出相应的响应，并且当捏手势发生时，简单地使布局无效。
例如，如果我想调整每个项目的大小，同时捏住：

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

@property (nonatomic,assign) CGFloat scale;
@property (nonatomic,weak)   IBOutlet UICollectionView *collectionView;

@end

@implementation ViewController
- (void)viewDidLoad
{
    [super viewDidLoad];

    self.scale = 1.0;

    [self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"cell"];

    UIPinchGestureRecognizer *gesture = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(didReceivePinchGesture:)];
    [self.collectionView addGestureRecognizer:gesture];

}

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
    return CGSizeMake(50*self.scale, 50*self.scale);
}

- (void)didReceivePinchGesture:(UIPinchGestureRecognizer*)gesture
{
    static CGFloat scaleStart;

    if (gesture.state == UIGestureRecognizerStateBegan)
    {
        scaleStart = self.scale;
    }
    else if (gesture.state == UIGestureRecognizerStateChanged)
    {
        self.scale = scaleStart * gesture.scale;
        [self.collectionView.collectionViewLayout invalidateLayout];
    }
}

属性self.scale仅用于显示，您可以将相同的概念应用于任何其他属性，这不需要beginUpdates/endUpdates，因为用户自己携带刻度的计时。
Here's a running project，如果您想查看它的实际操作。

对不起我的2美分的问题，我已经找到了解决办法，非常简单。
在我的PinchGesture回调中，我刚刚完成了以下操作：

void (^animateChangeWidth)() = ^() {
    _theFlowLayout.itemSize = cellSize;
};

[UIView transitionWithView:self.theCollectionView 
                  duration:0.1f 
                   options:UIViewAnimationOptionCurveLinear 
                animations:animateChangeWidth 
                completion:nil];

我的UICollectionView的所有单元格都成功地改变了，并有了一个不错的transition。

对于Xamarin.iOS开发者，我找到了这个解决方案：将UIScrollView元素添加到主视图，并将UICollectionView添加为UIScrollView的元素。然后为UIScrollView创建缩放委托。

MainScrollView = new UIScrollView(new CGRect(View.Frame.X, View.Frame.Y, size.Width, size.Height));

        
        _cellReuseId = GenCellReuseId();

        _contentScroll = new UICollectionView(new CGRect(View.Frame.X, View.Frame.Y, size.Width, size.Height), new InfiniteScrollCollectionLayout(size.Width, size.Height));
        
        _contentScroll.AllowsSelection = true;
        _contentScroll.ReloadData();

        _contentScroll.Center = MainScrollView.Center;
        _contentScroll.Frame = new CGRect(_contentScroll.Frame.X, _contentScroll.Frame.Y - 32, _contentScroll.Frame.Width, _contentScroll.Frame.Height);
        MainScrollView.ContentSize = _contentScroll.ContentSize;
        MainScrollView.AddSubview(_contentScroll);
        MainScrollView.MaximumZoomScale = 4f;
        MainScrollView.MinimumZoomScale = 1f;
        MainScrollView.BouncesZoom = true;
        MainScrollView.ViewForZoomingInScrollView += (UIScrollView sv) =>
        {
            if (_contentScroll.Frame.Height < sv.Frame.Height && _contentScroll.Frame.Width < sv.Frame.Width)
            {
                _contentScroll.Center = MainScrollView.Center;
                _contentScroll.Frame = new CGRect(_contentScroll.Frame.X, _contentScroll.Frame.Y - 64, _contentScroll.Frame.Width, _contentScroll.Frame.Height);
                _contentScroll.BouncesZoom = true;
                _contentScroll.AlwaysBounceHorizontal = false;
            }
            return _contentScroll;
};