How to position UITableViewCell at bottom of screen?

Question

There are one to three UITableViewCells in a UITableViewView. Is there a way to always position the cell(s) at the bottom of screen after rel

Answer 1

I didn't like empty-cell, contentInset or transform based solutions, instead I came up with other solution:

UITableView's layout is private and subject to change if Apple desires, it's better to have full control thus making your code future-proof and more flexible. I switched to UICollectionView and implemented special layout based on UICollectionViewFlowLayout for that (Swift 3):

override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
    // Do we need to stick cells to the bottom or not
    var shiftDownNeeded = false

    // Size of all cells without modifications
    let allContentSize = super.collectionViewContentSize()

    // If there are not enough cells to fill collection view vertically we shift them down
    let diff = self.collectionView!.bounds.size.height - allContentSize.height
    if Double(diff) > DBL_EPSILON {
        shiftDownNeeded = true
    }

    // Ask for common attributes
    let attributes = super.layoutAttributesForElements(in: rect)

    if let attributes = attributes {
        if shiftDownNeeded {
            for element in attributes {
                let frame = element.frame;
                // shift all the cells down by the difference of heights
                element.frame = frame.offsetBy(dx: 0, dy: diff);
            }
        }
    }

    return attributes;
}

It works pretty well for my cases and, obviously, may be optimized by somehow caching content size height. Also, I'm not sure how will that perform without optimizations on big datasets, I didn't test that. I've put together sample project with demo: MDBottomSnappingCells.

Here is Objective-C version:

- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect;
{
    // Do we need to stick cells to the bottom or not
    BOOL shiftDownNeeded = NO;

    // Size of all cells without modifications
    CGSize allContentSize = [super collectionViewContentSize];

    // If there are not enough cells to fill collection view vertically we shift them down
    CGFloat diff = self.collectionView.bounds.size.height - allContentSize.height;
    if(diff > DBL_EPSILON)
    {
        shiftDownNeeded = YES;
    }

    // Ask for common attributes
    NSArray *attributes = [super layoutAttributesForElementsInRect:rect];
    if(shiftDownNeeded)
    {
        for(UICollectionViewLayoutAttributes *element in attributes)
        {
            CGRect frame = element.frame;
            // shift all the cells down by the difference of heights
            element.frame = CGRectOffset(frame, 0, diff);
        }
    }

    return attributes;
}