How to change the background color from another ViewController?

Question

I have two view controllers, the Home and the other that is showed by a cocoacontrol animation (MJPopupViewController) and idn the one that is showed when you push a button all the background changes, but I dont know how to change the home view controller`s background because they are not in a navigation so I cant use a self.parentViewController casting, so how can I do this? Heres the code:

- (IBAction)purple:(id)sender {
    self.view.backgroundColor = [UIColor MyPurple];

    HomeViewController *home = (HomeViewController *) self.parentViewController; <-- this didnt work, I also tried only self....

    home.view.backgroundColor = [UIColor purpleColor];


}

So I need your help, Im starting so I hope you understand, thanks!

Use a delegate pattern: http://stackoverflow.com/questions/8606674/uimodaltransitionstylepartialcurl-doesnt-get-back-to-previous-state-not-dismi/8607949#8607949 — user523234, Mar 16 '14 at 01:29

klcjr89 · Accepted Answer · 2014-03-16T01:38:07.347

1

Perhaps try:

HomeViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

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

- (void)changeColor
{
    self.view.backgroundColor = [UIColor purpleColor];
}

- (void)dealloc
{
    [[NSNotificationCenter defaultCenter]removeObserver:self];
}

PopUpViewController

- (IBAction)purple:(id)sender
{
    [[NSNotificationCenter defaultCenter]postNotificationName:@"changeColor" object:nil];
}

edited Mar 16 '14 at 01:38

answered Mar 16 '14 at 01:07

klcjr89

5,862
10
58
91

mmm no didnt work, I dont know if its that but theres no navigation controller... – Karlo A. López Mar 16 '14 at 01:13
Well, that will be the issue. You need to get the index to the view controller in the heirarchy. – klcjr89 Mar 16 '14 at 01:15
Sorry but if its not too much trouble how can I do that? Its because Im starting and I dont get it.. Thanks – Karlo A. López Mar 16 '14 at 01:19
Well, are you using some kind of container view controller or a tab bar controller? How are your controllers being added to the stack? – klcjr89 Mar 16 '14 at 01:22
With this UIViewController Category https://github.com/martinjuhasz/MJPopupViewController – Karlo A. López Mar 16 '14 at 01:26
Have you tried using an NSNotification to change the background color? That will work – klcjr89 Mar 16 '14 at 01:34
Thank you so much! I know I needed an observer but i didnt know how to write it, thanks! – Karlo A. López Mar 16 '14 at 01:40

score 0 · Answer 2 · answered Mar 16 '14 at 01:07

I suggest you to change the background color of a 'view' you need to set the backgroundColor property on it. This implies that you have access to it. If it was all in one controller you would just use

self.view.backgroundColor = [UIColor redColor];

If it was in a navigation or similar based app, then you can access a views parentViewController and change the color on it as follows:

self.parentViewController.view.backgroundColor = [UIColor redColor];

If this is not possible then you can set an iVar on the second view controller when it is created that contains the instance of the viewController that you want to change the background color on.

MyViewController* secondViewController = [[MyViewController alloc] init];
secondViewController.bgColorNeedsChangingViewController = self;

Then in the secondViewController's logic

self.bgColorNeedsChangingViewController.view.backgroundColor = [UIColor redColor];

How to change the background color from another ViewController?

2 Answers2