UIBarButtonItem 左边间隙过大 解决方案

调用下面的方法，设置negativeSpacer.width = -15;就可以解决间隙过大的问题：

UIBarButtonItem *leftItem = [[UIBarButtonItem alloc] initWithCustomView:dayOrWeekButton];
self.navigationItem.leftBarButtonItem = leftItem;
[dayOrWeekButton release];
[leftItem release];
if ([[[[UIDevice currentDevice] systemVersion] substringToIndex:1] intValue]>=7)
{
UIBarButtonItem *negativeSpacer = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];
negativeSpacer.width = -15;
self.navigationItem.leftBarButtonItems = @[negativeSpacer, leftItem];
}else{
self.navigationItem.leftBarButtonItem = leftItem;
}