iOS7 UI兼容 导航栏按钮边框 UINavigationItem left and right padding

@implementation UINavigationItem (margin)

#if __IPHONE_OS_VERSION_MAX_ALLOWED > __IPHONE_6_1
- (void)setLeftBarButtonItem:(UIBarButtonItem *)_leftBarButtonItem
{
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0)
{
UIBarButtonItem *negativeSeperator = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];
negativeSeperator.width = -12;

if (_leftBarButtonItem)
{
[self setLeftBarButtonItems:@[negativeSeperator, _leftBarButtonItem]];
}
else
{
[self setLeftBarButtonItems:@[negativeSeperator]];
}
[negativeSeperator release];
}
else
{
[self setLeftBarButtonItem:_leftBarButtonItem animated:NO];
}
}

- (void)setRightBarButtonItem:(UIBarButtonItem *)_rightBarButtonItem
{
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0)
{
UIBarButtonItem *negativeSeperator = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];
negativeSeperator.width = -12;

if (_rightBarButtonItem)
{
[self setRightBarButtonItems:@[negativeSeperator, _rightBarButtonItem]];
}
else
{
[self setRightBarButtonItems:@[negativeSeperator]];
}
[negativeSeperator release];
}
else
{
[self setRightBarButtonItem:_rightBarButtonItem animated:NO];
}
}

#endif
@end