UICollectionView not able to scroll to see the ent

问题:

I have a UICollectionView with size: 768x1024 with a navbar on top. My custom UICollectionViewCells are of size 200x200. The problem is that when I keep adding cells and I reach the bottom row, I can only see part of the 200x200 cell. It won't let me scroll further before it bounces back up. Any ideas on what the problem could be?

EDIT:

I add cells via:

insertItemsAtIndexPaths:

回答1:

The issue was just adding AutoLayout constraints to the View Controller which housed the UICollectionView. To do this, select the View Controller in Storyboards and click on "Editor" on the top. Then, "Resolve Autolayout Issues" > "Reset to Suggested Constraints..."

回答2:

The problem has to do with your UICollectionViewLayout, since it is the job of the layout to state how large the actual scrollable content is, and to ask for a refresh of that information when necessary. But unfortunately your question reveals nothing about how you are doing layout or how you "keep adding cells", so no specific answer is possible.

EDIT (after your edit): It is not enough to call insertItemsAtIndexPaths:; you must also add the items to your model (the data source). Otherwise, the layout doesn't know about them and doesn't make the scrollable content bigger (and lots of other bad things happen too).

回答3:

i think you use the collection view in an unsual way, but if the content area of the scrollview of the collection view extend the frame size of the collection view you have to set the virtual size with the property 'contentSize' :

self.collectionView.contentSize = CGSizeMake(768,900);

回答4:

I had a similar problem but due a gradient that it was at the bottom of the collection view and the user was not able to see the last rows of the collection view.

The way I've found to solve it is in the Size Inspector, set the Height of the Footer Size to a number that works for issue.

I know that maybe, it's not the best solution. But it works for my problem and it's really easy to use it.

Collection View that doesn't show the last row:

Collection View after setting the Footer Size Height to 40: