一覧更新前後のタイミングが分かるUICollectionViewを実装する

@class UICollectionViewEx;

@protocol UICollectionViewExDelegate <NSObject, UICollectionViewDelegate>

@optional

- (void)willReloadDataByCollectionView:(UICollectionViewEx*)collectionView;

- (void)didReloadDataByCollectionView:(UICollectionViewEx*)collectionView;

@end

// 拡張機能を持たせたUICollectionView

@interface UICollectionViewEx : UICollectionView

@property (nonatomic, assign) id<UICollectionViewExDelegate> delegate;

@end

@implementation UICollectionViewEx

@dynamic delegate;

- (id)initWithFrame:(CGRect)frame

{

    self = [super initWithFrame:frame];

    if (self) {

        // Initialization code

    }

    return self;

}

- (void)reloadData

{

if ([self.delegate respondsToSelector:@selector(willReloadDataByCollectionView:)]) {

[self.delegate willReloadDataByCollectionView:self];

}

[super reloadData];

if ([self.delegate respondsToSelector:@selector(didReloadDataByCollectionView:)]) {

[self.delegate didReloadDataByCollectionView:self];

}

}

@end