ios -- 添加分段控件到导航条并居中

   NSArray *arr = @[@"消息",@"通知"];
    UISegmentedControl *segmentedControl = [[UISegmentedControl alloc] initWithItems:arr];
    segmentedControl.frame = CGRectMake(0, 0, 100, 30);
    
    segmentedControl.selectedSegmentIndex = 0;
    
    segmentedControl.tintColor = [UIColor blueColor];
    
    segmentedControl.segmentedControlStyle = UISegmentedControlStyleBar;
    
    [segmentedControl addTarget:self action:@selector(indexDidChangeForSegmentedControl:)
     
               forControlEvents:UIControlEventValueChanged];
//    self.navigationController.navigationItem.titleView = segmentedControl;
    [self.navigationItem setTitleView:segmentedControl];
    

}

- (void)indexDidChangeForSegmentedControl:(id)sender {
    if ([sender selectedSegmentIndex] == 0) {
        self.view.backgroundColor = [UIColor redColor];
    } else if ([sender selectedSegmentIndex] == 1) {
        self.view.backgroundColor = [UIColor blueColor];
    }
}