Adding a UILabel to a UIToolbar（在工具条上添加一个UILabel）

I'm trying to add a label to my toolbar. Button works great, however when I add the label object, it crashes. Any ideas?
我试图往工具栏上面添加一个UILabel，之前添加的button很好用，然而当我添加完UIlabel，程序崩溃了？谁能告诉我这是为什么？
下面是源代码：

UIBarButtonItem *setDateRangeButton = [[UIBarButtonItem alloc] initWithTitle:@"Set date range" style:UIBarButtonItemStyleBordered target:self action:@selector(setDateRangeClicked:)];
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(5, 5, 20, 20)];label.text = @"test";
[toolbar setItems:[NSArray arrayWithObjects:setDateRangeButton,label, nil]];
// Add the toolbar as a subview to the navigation controller.
[self.navigationController.view addSubview:toolbar];
// Reload the table view
[self.tableView reloadData];

工具栏可以通过添加SpaceItem来进行布局

NSMutableArray *items = [[self.toolbar items] mutableCopy];

UIBarButtonItem *spacer = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
[items addObject:spacer];

self.titleLabel = [[UILabel alloc] initWithFrame:CGRectMake(0.0 , 11.0f, self.view.frame.size.width, 21.0f)];
[self.titleLabel setFont:[UIFont fontWithName:@"Helvetica-Bold" size:18]];[self.titleLabel setBackgroundColor:[UIColor clearColor]];
[self.titleLabel setTextColor:[UIColor colorWithRed:157.0/255.0 green:157.0/255.0 blue:157.0/255.0 alpha:1.0]];
[self.titleLabel setText:@"Title"];
[self.titleLabel setTextAlignment:NSTextAlignmentCenter];

UIBarButtonItem *spacer2 = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
[items addObject:spacer2];

UIBarButtonItem *title = [[UIBarButtonItem alloc] initWithCustomView:self.titleLabel];
[items addObject:title];

[self.toolbar setItems:items animated:YES];```

可以将UILabel转化为UIView 添加到Item的customerView上面

UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(140 , 0, 50, 250)];
[label setBackgroundColor:[UIColor clearColor]];label.text = @"TEXT";
UIView *view = (UIView *) label;
[self.barItem setCustomView:view];```