ios programming cookTips

CGRect frame, remain;
    CGRectDivide(self.view.bounds, &frame, &remain, 44, CGRectMaxYEdge);
    _toolbar = [[UIToolbar alloc] initWithFrame:frame];
//    _toolbar.autoresizingMask = UIViewAutoresizingFlexibleTopMargin;
    UIBarButtonItem *button1 = [[UIBarButtonItem alloc] initWithTitle:@"今天" style:UIBarButtonItemStyleDone target:self action:@selector(toolBarGotoToday)];
    UIBarButtonItem *spacer = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:self action:nil];
    
    UIBarButtonItem *button2=[[UIBarButtonItem alloc]initWithImage:[UIImage imageNamed:@"schedule_back"] style:UIBarButtonItemStylePlain target:self action:@selector(toolbarBackClick)];
    [_toolbar setItems:[[NSArray alloc] initWithObjects:button1,spacer,button2,nil]];
//    [_toolbar setAutoresizingMask:UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleTopMargin];
//    [self.view addSubview:_toolbar];

self.navigationController.toolbarHidden = NO;
    self.toolbarItems = @[button1,spacer,button2];