How to eliminate the left and right margins of a grouped UITableView - objective-c

Question

If I have a grouped UITableView, it comes with a grayish border/buffer around the edge of it. Is there any way to tell how large this buffer is, or equivalently, how big the actual white cell inside it is?

Answer 1

This is how you can eliminate the left and right margins of a grouped UITableView. Just subclass UITableViewCell. Note that if you want the margin to be something other than 0 just change the setFrame method to suit your needs.
//In CustomGroupedCell.h
#import <UIKit/UIKit.h>
#interface CustomGroupedCell : UITableViewCell
#property (nonatomic, weak) UITableView *myTableView;
#end
//In CustomGroupedCell.m
#import "CustomGroupedCell.h"
#implementation CustomGroupedCell
#synthesize myTableView = _myTableView;
- (void)setFrame:(CGRect)frame
{
frame = CGRectMake(- [self cellsMargin] , frame.origin.y, self.myTableView.frame.size.width + 2 *[self cellsMargin], frame.size.height);
self.contentView.frame = frame;
[super setFrame:frame];
}
- (CGFloat)cellsMargin {
// No margins for plain table views
if (self.myTableView.style == UITableViewStylePlain) {
return 0;
}
// iPhone always have 10 pixels margin
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
{
return 10;
}
CGFloat tableWidth = self.myTableView.frame.size.width;
// Really small table
if (tableWidth <= 20) {
return tableWidth - 10;
}
// Average table size
if (tableWidth < 400) {
return 10;
}
// Big tables have complex margin's logic
// Around 6% of table width,
// 31 <= tableWidth * 0.06 <= 45
CGFloat marginWidth = tableWidth * 0.06;
marginWidth = MAX(31, MIN(45, marginWidth));
return marginWidth;
}
#end