ios - 通过捏合手势缩放 UICollectionView

Question

我有一个UICollectionView里面有很多细胞（大约 5k+）。我想捏一下放大/缩小。我已经尽力了invalidateLayout。它真的很慢。所以我想使用CGAffineTransformMakeScale，但我不知道如何在此之后滚动。我的代码是：

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

if (gesture.state == UIGestureRecognizerStateBegan) {
    scaleStart = self.venueLayoutZoom;
}
else if (gesture.state == UIGestureRecognizerStateChanged) {
    CGAffineTransform transform = CGAffineTransformMakeScale(self.venueLayoutZoom, self.venueLayoutZoom);
    self.activeCollectionNode.view.transform = transform;
    self.activeCollectionNode.view.contentSize = CGSizeMake(318 * self.venueLayoutZoom, 500 * self.venueLayoutZoom);
}
}

但是当放大时我无法左右滚动。帮帮我。

Answer 1

利用

@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];
  }
  }