In my case the solution was to create a headerview for the table and assign a color, it solved the black background in bounce area in my apps when in dark mode. I did the same to its tableFooterView.

 table.tableHeaderView = UIView()
 table.tableHeaderView!.backgroundColor = UIColor.white
    

EASIEST SOLUTION

The easiest way to create different colors in the bottom and in the top of a bouncing area of a table view is to set the key tableHeaderBackgroundColor of the table view. Doing this way you set the top color. I'm not sure, but maybe there is another key for the footer, take a look. If you don't find anything, you just have to set the background of the table view with the color that you want to show in the bottom. Above you can see an example code:

self.table.setValue(UIColor.blue , forKey: "tableHeaderBackgroundColor")

Hope it help you. If yes, let other people know about this easy way giving an up in the answer :)

This code works in Swift fot UITableView:

var frame = self.tableView.bounds
frame.origin.y = -frame.size.height
frame.size.height = frame.size.height
frame.size.width = UIScreen.mainScreen().bounds.size.width
let blueView = UIView(frame: frame)
blueView.backgroundColor = UIColor.headerBlueColor()
self.tableView.addSubview(blueView)

In Swift (tested on iOS9)

    let backView = UIView(frame: self.tableView.bounds)
    backView.backgroundColor = UIColor.clearColor() // or whatever color
    self.tableView.backgroundView = backView

To extend on HusseinB's suggestion:

Swift 3

let bgView = UIView()
bgView.backgroundColor = UIColor.white
self.tableView.backgroundView = bgView

Objective C

UIView *bgView = [UIView new];
bgView.backgroundColor = [UIColor whiteColor];
[self.tableView setBackgroundView:bgView];

As of iOS 7, you can tinker this by changing the tableview background view.

[self.tableView setBackgroundView:view];

make the view's background colour the same as your parent view colour.

I just encountered this issue myself and found a solution.

Cause

I used Spark Inspector to examine the layout of the table view - which really helped.

Thing is, that in this scenario the UITableView has 3 subviews:

1. UITableViewWrapperView
2. UIView - With backgroundColor set to light gray color
3. UISearchBar

While you swipe the tableview content downwards, the second subview height is dynamically increasing to fill the space between the UITableViewWrapperView and the UITableView frame origin.

Solution

Setting the backgroundColor or backgroundView property won't effect the 2nd subview. What you need to do is find the second view and change its color, like so:

if (_tableView.subviews.count > 1) {
    _tableView.subviews[1].backgroundColor = THE_TARGET_COLOR;
}

In my case I needed all views to be white so I used the following which is less prone to future changes of UITableView view hierarchy by Apple:

for (UIView *subview in _tableView.subviews) {
    subview.backgroundColor = [UIColor whiteColor];
}

For anyone who's wondering how to do the same for the bottom bounce area:

First add a subview with your desired background color to your table view's background view:

self.bottomView = [[UIView alloc] initWithFrame:CGRectOffset(self.tableView.frame, 0, self.tableView.frame.size.height)];
self.bottomView.backgroundColor = whateverColorYouLike;

[self.tableView.backgroundView addSubview:self.bottomView];

And then in your table view's delegate:

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    CGRect frame = self.bottomView.frame;
    frame.origin.y = self.tableView.contentSize.height - self.tableView.contentOffset.y;
    self.bottomView.frame = frame;
}

I will give you the best way to do this.
First set the background color of the table view to the one you want in interface builder.
Then respond to the UITableView delegate tableView:willDisplayCell:ForIndexPath: method like this

- (void)tableView:(UITableView*)tableView willDisplayCell:(UITableViewCelll*)cell forIndexPath:(NSINdexPath*)indexPath
{
     [cell setBackgroundColor:[UIColor whiteColor]];
}

Another Method is :
in ViewDidLoad method (or anywhere you like) set the tableView background color to clear color like this:

self.tableView.backgroundColor = [UIColor clearColor];

and then set the superview color to white

self.tableView.superview.backgroundColor = [UIColor whiteColor];

I followed the tip outlined by Peylow, for a UITableView, by simply adding a subview. My only change from the code was to grab a color a bit closer to the one used in Apple apps, plus I got it a bit closer to Apple's look of having a line above the UISearchbar by reducing the frame origin y coordinate by one pixel:

frame.origin.y = -frame.size.height - 1

This is one of my very favorite tricks.

UIView *topview = [[[UIView alloc] initWithFrame:CGRectMake(0,-480,320,480)] autorelease];
topview.backgroundColor = [UIColor colorWithRed:226.0/255.0 green:231.0/255.0 blue:238.0/255.0 alpha:1];

[self.tableView addSubview:topview];

Basically you're creating a big view the size of the screen and placing it "above" the content area. You'll never be able to scroll up past it.

And don't worry about the memory impact of a UIView that's 320x480 pixels, it won't consume any significant memory because the CALayer doesn't have any meaningful content.

NOTE: Why is this answer relevant when the "accepted" answer is so much simpler? Why not just set the backgroundView on the table view? It's because, in the case of the Contacts app as shown in the original question, the area "above" the table view has a different background color (light blue) than the area "below" the table view (white). This technique allows you to have two different colors above and below the table view, which cannot be accomplished by a simple background.

EDIT 1/2018: As Tom in the comments pointed out, this answer is quite old and assumes that all iOS devices have the same screen size (seems crazy but it was the case in 2009 when I answered this). The concept I present here still works, but you should use UIScreen.main.bounds to figure out the actual screen size, or you could get into some fancy auto layout stuff (suggestions welcome). I don't recommend using tableView.bounds as in another answer, because typically in viewDidLoad the size of your views is not necessarily the size that they will become after the controller resizes them. Sometimes they start out as 0x0!

Setting transparencies is bad for performance. What you want is the gray area above the search bar, but it should still be white beyond the end of the list.

You can add a subview to your UITableView that lives above the content instead.

CGRect frame = self.list.bounds;
frame.origin.y = -frame.size.height;
UIView* grayView = [[UIView alloc] initWithFrame:frame];
grayView.backgroundColor = [UIColor grayColor];
[self.listView addSubview:grayView];
[grayView release];

You could add more fancy stuff to the view if you like, perhaps a fade, or a divider line without subclassing UISearchBar.

I've only found one way to do this. You have to set the backgroundColor of the UITableView to be transparent, set the backgroundColor of the cell's contentView to whatever colour you want the actual cells to be, then crucially you have to get the light grey colour to appear behind the UITableView. That last step you can do by either setting the backgroundColour of the UIWindow, or of whatever is containing or your tableViewController.

So, assuming you have a view controller that is derived from UITableViewController, insert these lines in the -(void)viewDidLoad method:-

// sets the background of the table to be transparent
self.tableView.backgroundColor = [UIColor colorWithWhite:1.0 alpha:0.0];
// assuming we are inside a navigation or tab controller, set the background
self.parentViewController.view.backgroundColor = [UIColor lightGrayColor];

Then inside the part of tableView:cellForRowAtIndexPath: that creates new cells, add:-

// set an opaque background for the cells 
cell.contentView.backgroundColor = [UIColor whiteColor];

I'm sure that that is [UITableView backgroundColor]. You have affected rows, because rows have backgroundColor == clear (or semi-transparent). So, If you'll make rows non-trasparent, all will work fine. This will be solution.

If you are using a tableviewcell, you can set the view background to be opaque white. Then use

self.tableView.backgroundColor = [UIColor grayColor];

in the view did load method.

I don't think you want to override drawRect. Most likely what you're seeing is the background colour of another view or the window, which lies "behind" (i.e. is a superview of) the table view. There's usually a fairly complex layers of UIViews in Apple's UI widgets. Explore the view hierarchy in GDB, look at [myView superview] and then [someSuperView subviews] and try manipulating their BG colours in the debugger to see if you can find which one it is. However, if you implement a fix this way, be warned that it may not be future compatible.

You might also try setting the BG colour of one of the views behind the tableview in Interface Builder (or of the window itself).