How can a UITableViewCell know of its own indexPath?

Question

The standard Grouped UITableView style allows UITableViewCells to be drawn with rounded corners at the top and bottom of each section. How is this accomplished? How does the cell know its own location within its section, and how does it know when to change its rounded edges?

I want to make my own rounded cells, and I have images to use, but don't know when to show which image

Note: I already know how the UITableView works, and I know how to use it. I just thought that since a UITableView is able to automatically draw rounded corners at the correct places, I should be able to as well, without needing to add anything to my data source or delegate.

Answer 1

NSIndexPath *indexPath = [(UITableView *)self.superview indexPathForCell: self]; int rows = [(UITableView *)self.superview numberOfRowsInSection:indexPath.section];  if (indexPath.row == 0 && rows == 1) { // the one and only cell in the section } else if (indexPath.row == 0) { //top } else if (indexPath.row != rows - 1) { //middle } else { //bottom } 

Answer 2

It's very simple. suppose cell is the object, whose position is to be found out.

  UITableView* table = (UITableView *)[cell superview];    NSIndexPath* pathOfTheCell = [table indexPathForCell:cell];    NSInteger sectionOfTheCell = [pathOfTheCell section];    NSInteger rowOfTheCell = [pathOfTheCell row]; 

Answer 3

There is sectionLocation method of UITableViewCell that returns integer telling you what you need:

• 1 - middle cell
• 2 - top cell
• 3 - bottom cell
• 4 - single cell

I had no issues using this in several production apps since 2010.

UPDATE: one of our binaries was automatically rejected recently (end of 2018) because we were using 'sectionLocation' property, so it's not a good option anymore.

Add something like this into your header files and you can use it:

typedef NS_ENUM(NSInteger, MMMTableViewCellLocation) {

    MMMTableViewCellLocationUndefined = 0,
    MMMTableViewCellLocationMiddle = 1,
    MMMTableViewCellLocationTop = 2,
    MMMTableViewCellLocationBottom = 3,
    MMMTableViewCellLocationSingle = 4
};

@interface UITableViewCell ()

/** Undocumented method of UITableViewCell which allows to know where within section the cell is located,
 * so the cell can draw its borders properly. */
- (MMMTableViewCellLocation)sectionLocation;

/** Override this one to know when the value of sectionLocation changes. */
- (void)setSectionLocation:(MMMTableViewCellLocation)sectionLocation animated:(BOOL)animated;

@end