// viewController
@interface ViewController ()

@property (nonatomic, strong) AXECollectionView *collectionView;

@end

@implementation ViewController

- (void)viewDidLoad {
  [super viewDidLoad];

  // 流水布局
  UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init];
  flowLayout.minimumLineSpacing = kItem_Margin;
  flowLayout.minimumInteritemSpacing = [UIScreen mainScreen].bounds.size.height;
  flowLayout.itemSize = CGSizeMake([UIScreen mainScreen].bounds.size.width - kItem_Margin, kItem_Height);
  flowLayout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
  flowLayout.sectionInset = UIEdgeInsetsMake(0, kItem_Margin / 2, 0, kItem_Margin / 2);

  CGRect frame = self.view.bounds;
  _collectionView = [[AXECollectionView alloc] initWithFrame:frame collectionViewLayout:flowLayout];

  // 传入图片数组
  _collectionView.imgArr = @[
                @"0",
                @"1",
                @"2",
                @"3",
                @"4",
                @"5",
                @"6",
                @"7",
                ];

  [self.view addSubview:_collectionView];
}

// AXECollectionView.h
@interface AXECollectionView : UICollectionView

@property (nonatomic, strong) NSArray *imgArr;

@end


// AXECollectionView.m
@interface AXECollectionView () <UICollectionViewDelegate, UICollectionViewDataSource>

// 背景imgView
@property (nonatomic, strong) UIImageView *bgImgView;

@end

@implementation AXECollectionView

static NSString *const AXECollectionViewCellID = @"AXECollectionViewCell";

- (instancetype)initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionViewLayout *)layout
{
  if(self = [super initWithFrame:frame collectionViewLayout:layout])
  {
    [self setup];
  }
  return self;
}

- (void)setup
{
  self.showsVerticalScrollIndicator = NO;
  self.showsHorizontalScrollIndicator = NO;
  self.pagingEnabled = YES;
  self.dataSource = self;
  self.delegate = self;
  [self registerClass:[AXECollectionViewCell class] forCellWithReuseIdentifier:AXECollectionViewCellID];

  // collectionView背景view
  UIImageView *bgImgView = [[UIImageView alloc] initWithFrame:self.bounds];
  self.backgroundView = bgImgView;
  self.bgImgView = bgImgView;

  // 毛玻璃效果 (iOS8.0以后适用)
  UIBlurEffect *blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];
  UIVisualEffectView *effectView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];
  effectView.frame = self.bounds;
  [self.backgroundView addSubview:effectView];
}

#pragma mark - UICollectionViewDataSource

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
  AXECollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:AXECollectionViewCellID forIndexPath:indexPath];
  cell.img = self.imgArr[indexPath.row];

  // 设置毛玻璃图片
  self.bgImgView.image = [UIImage imageNamed:self.imgArr[indexPath.row]];
  return cell;
}

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
  return self.imgArr.count;
}

#pragma mark - UICollectionViewDelegate

- (void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath
{
  AXECollectionViewCell *myCell = (AXECollectionViewCell *)cell;
  [UIView animateWithDuration:0.5 animations:^{
    myCell.transform = CGAffineTransformScale(CGAffineTransformIdentity, 1.0, 1.4);
  }];
}

// 返回滤镜处理后图片
- (UIImage *)coreBlurImage:(UIImage *)image withBlurNumber:(CGFloat)blur
{
  CIContext *context = [CIContext contextWithOptions:nil];
  CIImage *inputImage= [CIImage imageWithCGImage:image.CGImage];

  // 设置filter
  CIFilter *filter = [CIFilter filterWithName:@"CIGaussianBlur"];
  [filter setValue:inputImage forKey:kCIInputImageKey];
  [filter setValue:@(blur) forKey: @"inputRadius"];

  // 模糊图片
  CIImage *result=[filter valueForKey:kCIOutputImageKey];
  CGImageRef outImage=[context createCGImage:result fromRect:[result extent]];
  UIImage *blurImage=[UIImage imageWithCGImage:outImage];
  CGImageRelease(outImage);
  return blurImage;
}

// 返回高斯效果模糊图片
- (UIImage *)boxblurImage:(UIImage *)image withBlurNumber:(CGFloat)blur
{
  if (blur < 0.f || blur > 1.f) {
    blur = 0.5f;
  }
  int boxSize = (int)(blur * 40);
  boxSize = boxSize - (boxSize % 2) + 1;
  CGImageRef img = image.CGImage;
  vImage_Buffer inBuffer, outBuffer;
  vImage_Error error;
  void *pixelBuffer;

  // 从CGImage中获取数据
  CGDataProviderRef inProvider = CGImageGetDataProvider(img);
  CFDataRef inBitmapData = CGDataProviderCopyData(inProvider);

  // 设置从CGImage获取对象的属性
  inBuffer.width = CGImageGetWidth(img);
  inBuffer.height = CGImageGetHeight(img);
  inBuffer.rowBytes = CGImageGetBytesPerRow(img);
  inBuffer.data = (void*)CFDataGetBytePtr(inBitmapData);
  pixelBuffer = malloc(CGImageGetBytesPerRow(img) * CGImageGetHeight(img));
  if(pixelBuffer == NULL)
    NSLog(@"No pixelbuffer");
  outBuffer.data = pixelBuffer;
  outBuffer.width = CGImageGetWidth(img);
  outBuffer.height = CGImageGetHeight(img);
  outBuffer.rowBytes = CGImageGetBytesPerRow(img);
  error = vImageBoxConvolve_ARGB8888(&inBuffer, &outBuffer, NULL, 0, 0, boxSize, boxSize, NULL, kvImageEdgeExtend);
  if (error) {
    NSLog(@"error from convolution %ld", error);
  }
  CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
  CGContextRef ctx = CGBitmapContextCreate( outBuffer.data, outBuffer.width, outBuffer.height, 8, outBuffer.rowBytes, colorSpace, kCGImageAlphaNoneSkipLast);
  CGImageRef imageRef = CGBitmapContextCreateImage (ctx);
  UIImage *returnImage = [UIImage imageWithCGImage:imageRef];

  // clean up
  CGColorSpaceRelease(colorSpace);
  free(pixelBuffer);
  CFRelease(inBitmapData);
  CGColorSpaceRelease(colorSpace);
  CGImageRelease(imageRef);
  return returnImage;
}