从另一个视图IOS更改滚动条背景

Question

This is HomeView enter image description here

When Someone tapped in 'Banking' button . Action will load BaseviewController .

This is the button action.

HomeViewController.m

BaseViewController *clickbutton  = [[BaseViewController alloc] initWithNibName:@"BaseViewController" bundle:nil] ;
[self presentViewController:clickbutton animated:YES completion:nil];

This is BaseView enter image description here

There is a scrollbar which will load every view . The scrollbar background is Green . And change the background in next here is the problem .

BaseViewController.m

-(void)ViewDidLoad{

   PriorityViewController  *obj ;

   UINavigationController *nav;

   obj  = [[ PriorityViewController alloc]  initWithNibName:@"PriorityViewController" bundle:nil] ;

   nav = [[UINavigationController alloc] initWithRootViewController:obj];

   nav.view.frame = rect;

   [self.view addSubview:self.nav.view];

 }

When tapped 'Service Request' .

  OtherBankTransferViewController *obj;
  obj  = [[OtherBankTransferViewController   alloc]initWithNibName:@"OtherBankTransferViewController" bundle:nil];

[self.navigationController  pushViewController:obj animated:YES  ];

This will load same as like second image I uploaded here . I just want to change my background color of the scrollbar I want to change scrollbar into black color .

I have no idea . If someone explain me ! Thanks in advance .

Answer 1

APPROACH 1: Instead of initialising scrollBar in each ViewController, why not alloc init it in BaseView Controller and pass instance of it to all View Controller. Since now all ViewControllers will have same instance it will be easy to change background of the scrollBar.

APPROACH 2: You can post notifications whenever you want to change the scrollBar color, add observer for the notification you are posting and with the notification you can pass the color you want to be set for all scrollBar.

Posting Notification when you want to change color

NSDictionary *userInfo = [NSDictionary dictionaryWithObject:[UIColor blackColor] forKey:@"someKey"];
[[NSNotificationCenter defaultCenter] postNotificationName: @"TestNotification" object:nil userInfo:userInfo];

Adding Observer in viewDidLoad

[[NSNotificationCenter defaultCenter] addObserver:self
    selector:@selector(receiveTestNotification:) 
    name:@"TestNotification"
    object:nil];

Method to handle received Notification

- (void) receiveTestNotification:(NSNotification *) notification{

    NSDictionary *userInfo = notification.userInfo;
    UIColor *backGroundColor = [userInfo objectForKey:@"someKey"];
    // assign this color to your scrollBar in each ViewController

}

REMOVING OBSERVER in viewDidUnload

[[NSNotificationCenter defaultCenter] removeObserver:self name:@"TestNotification" object:nil];