Grouped UITableView has 20px of extra padding at the bottom

@frankWhite' solution works great, but here is a better solution to avoid typing 0.1, 0.001 or others to make it less ambiguous.

// Swift version
func tableView(tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat {

    // remove bottom extra 20px space.
    return CGFloat.min
}

// Objective-C version
- (CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section {

    // remove bottom extra 20px space.
    return CGFLOAT_MIN;
} 

You can use contentInset to compensate the 20px extra bottom margin:

tableView.contentInset = UIEdgeInsetsMake(0, 0, -20, 0);

in Swift 3

override func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat {
    return CGFloat.leastNormalMagnitude
}

-(CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section {
   return 0.01;
} 

It's work for me

This is the only working solution I guess.I tried setting tableFooterView and tableHeaderView to nil. But nothing happened.Then the following solution worked .Returning zero "return 0;" has no effect.We should return the lowest possible height.

 - (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section {
        return CGFLOAT_MIN;
    }

 - (CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section {
        return CGFLOAT_MIN;
    }

NOTE: This is what I got when printed the values.

CGFLOAT_MAX = 340282346638528859811704183484516925440.000000 CGFLOAT_MIN = 0.000000

Recently, I found this issue, and followed the solutions posted above, but all of them doesn't work. In my case, I have a section header with dynamic height. Inspired by the above solutions, I put following code, and problem solved. I hope this can help.

func tableView(_ tableView: UITableView, viewForFooterInSection section: Int) -> UIView? {
    return UIView()
}

func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat {
    return 0.1
}

and config tableView's header and footer like this:

tableView.tableHeaderView = UIView(frame: CGRect(x: 0, y: 0, width: 1, height: 0.1))
tableView.tableFooterView = UIView(frame: CGRect(x: 0, y: 0, width: 1, height: 0.1))

In Swift 4.2 you can try setting table header with least normal magnitude height -

var frame = CGRect.zero
frame.size.height = .leastNormalMagnitude
tableView.tableHeaderView = UIView(frame: frame)

this solves the issue:

Obj-c

- (CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section {
        return 0.1;
    }

Swift:

override func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat {
    return 0.1
}

Following code works for me

- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section {
    return 0;
}

- (CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section {
    return 0;
}

Swift 3 code

class PaddingLessTableView : UITableView
{
    override func layoutSubviews() {
        self.contentInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
        super.layoutSubviews()
    }
}

Swift 5

 tableView.tableHeaderView = UIView(frame: CGRect(x: 0, y: 0, width: view.frame.width, height: .leastNormalMagnitude))

Use the bounces property of UIScrollView:

[yourTableView setBounces:NO];

This will remove what seems to be an extra padding at the top and bottom of your UITableView. Actually, it will just disable the tableview's scrollview to scroll past the edge of the content.