谁能告诉我这个错误代码中发生了什么
[UIViewController collectionView:numberOfItemsInSection:]: unrecognized selector sent to instance 0x8c9a6d0
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIViewController collectionView:numberOfItemsInSection:]: unrecognized selector sent to instance 0x8c9a6d0'
collectionView代码是
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return [array count];
}
我做错了什么