[UIKit] CollectionView의 contentSize는 언제 할당 되는가? : view 가 그려지고 layout이 계산 되는 순서

호출 순서

1. viewDidLoad { print(collectionView.collectionViewLayout.collectionViewContentSize.height) }
-> 0.0

2. viewWillAppear { print(collectionView.collectionViewLayout.collectionViewContentSize.height) }
-> 0.0

3. viewWillLayoutSubViews { print(collectionView.collectionViewLayout.collectionViewContentSize.height) }
-> 0.0

4. viewDidLayoutSubviews { print(collectionView.collectionViewLayout.collectionViewContentSize.height) }
-> 0.0

5. collectionView numberOfItesmInSection{}

6. collectionView cellForItemAt{ print(collectionView.collectionViewLayout.collectionViewContentSize.height) }
-> 1284.0

7. viewWillLayoutSubViews { print(collectionView.collectionViewLayout.collectionViewContentSize.height) }
-> 1284.0

8. viewDidLayoutSubViews { print(collectionView.collectionViewLayout.collectionViewContentSize.height) }
-> 1284.0

5. viewDidAppear { print(collectionView.collectionViewLayout.collectionViewContentSize.height) }
-> 1284.0