iOS中自定义导航栏左边返回按钮和按钮不能靠左的问题

//自定义左边 的按钮
UIButton *leftButton = [[UIButton
alloc]init];
leftButton.frame =
CGRectMake(0,
0, 20,
20);
[leftButton
setBackgroundImage:[UIImage
imageNamed:@"返回.png"]
forState:UIControlStateNormal];
[leftButton
addTarget:self
action:@selector(popToLastVC:)
forControlEvents:UIControlEventTouchUpInside];
UIBarButtonItem *leftBarButtonItems = [[UIBarButtonItem
alloc]initWithCustomView:leftButton];
//解决按钮不靠左 靠右的问题.
UIBarButtonItem *nagetiveSpacer = [[UIBarButtonItem
alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace
target:nil
action:nil];
nagetiveSpacer.width = -15;//这个值可以根据自己需要自己调整
self.navigationItem.leftBarButtonItems =
@[nagetiveSpacer, leftBarButtonItems];