Change UIButton alpha from different class

Question

Hey guys!

I want to change the alpha of a UIButton which sounds actually pretty simple. However, I want to change that alpha from a different class(ViewControllerB.m/.h). I got a class called "ViewController.h/.m" and from this class I call a view which appears on the ViewController like a popup. Now I got a UIButton which displays the popup, when it's touched. If the button was touched its alpha will change to "0.0" and the popup will be shown. I got the code from the popup in another class and I want to change the alpha of the button to "1.0" if the pupup was dismissed. I already got a method, that is called when the popup was dismissed. I tried everything, but it didn't worked so far. Maybe because I'm a beginner at iOS ^^.

I hope you understood what I am trying to say. I will leave the code as it is (clean) to do not confuse you with the ways I tried before.

Here you got the codes of my classes:

ViewController.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController {
//....
    IBOutlet UIButton *myBtn;
//...
}

- (IBAction)OpenPopUp:(id)sender;

Now in my ViewController.m:

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

//...viewDidLoad....everything else

- (IBAction)OpenPopUp:(id)sender {
 [UIView animateWithDuration: 1.0
                     animations:^{
    myBtn.alpha = 0.0;
                     }];

}

@end

In my ViewControllerB.h:

#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>

@interface ViewControllerB : UIViewController {
//...some unneccesary outlets
}

//Displaying popup.....
- (void)presentInParentViewController:(UIViewController *)parentViewController;

@end

ViewControllerB.m :

#import "ViewControllerB.h"

@interface ViewControllerB () 

@end

@implementation

//...ViewDidload...and more

- (IBAction)close:(id)sender {
    //The close button
    [self dismissFromParentViewController];
}

- (void)dismissFromParentViewController {
    //Removes the nutrition view from the superview

    [self willMoveToParentViewController:nil];

    //Removes the view with or without animation
    if (!self.shouldAnimateOnDisappear) {
        [self.view removeFromSuperview];
        [backgroundGradientView removeFromSuperview];
        [self removeFromParentViewController];
        return;
    }
    else {
        [UIView animateWithDuration:0.4 animations:^ {
            CGRect rect = self.view.bounds;
            rect.origin.y += rect.size.height;
            self.view.frame = rect;
            backgroundGradientView.alpha = 0.0f;
        }
                         completion:^(BOOL finished) {
                             [self.view removeFromSuperview];
                             [backgroundGradientView removeFromSuperview];
                             [self removeFromParentViewController];
                         }];
    }
//THE PLACE I WANT TO CHANGE THE ALPHA BACK!
}

I really would appreciate anyones help and if you can please show it me on code examples.

Thank you,

Noah

NOTE: I already looked up this posts but tried unsuccsessfully.

Anshul Jain · Accepted Answer · 2013-10-15T07:02:48.583

There are 2 ways of doing it,

In ViewController *viewDidAppear:* method check myBtn alpha. if alpha is zero then set the alpha back to 1.
You can add ViewController as a delegate in ViewControllerB and ViewControllerB notifies ViewController when it is dismissed and then you set the alpha of myBtn back to 1

In my ViewControllerB.h:

#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>

@protocol ViewControllerBDelegate <NSObject>
   - (void)didHidePopoverController
@end

@interface ViewControllerB : UIViewController {
//...some unneccesary outlets
}
@property(readwrite,weak)id <ViewControllerBDelegate>delegate;
//Displaying popup.....
- (void)presentInParentViewController:(UIViewController *)parentViewController;

@end

ViewController.h

#import <UIKit/UIKit.h>
#import "ViewControllerB.h"
@interface ViewController : UIViewController<ViewControllerBDelegate> {
//....
    IBOutlet UIButton *myBtn;
//...
}

- (IBAction)OpenPopUp:(id)sender;

@end

Now in ViewController.m:

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

//...viewDidLoad....everything else

- (IBAction)OpenPopUp:(id)sender {
 [UIView animateWithDuration: 1.0
                     animations:^{
    myBtn.alpha = 0.0;
                     }];

}

 - (void)didHidePopoverController {
 [UIView animateWithDuration: 1.0
                     animations:^{
    myBtn.alpha = 1.0;
                     }];

}


@end

ViewControllerB.m :

#import "ViewControllerB.h"

@interface ViewControllerB () 

@end

@implementation

//...ViewDidload...and more

- (IBAction)close:(id)sender {
    //The close button
    [self dismissFromParentViewController];
}

- (void)dismissFromParentViewController {
    //Removes the nutrition view from the superview

    [self willMoveToParentViewController:nil];

    //Removes the view with or without animation
    if (!self.shouldAnimateOnDisappear) {
        [self.view removeFromSuperview];
        [backgroundGradientView removeFromSuperview];
        [self removeFromParentViewController];
        return;
    }
    else {
        [UIView animateWithDuration:0.4 animations:^ {
            CGRect rect = self.view.bounds;
            rect.origin.y += rect.size.height;
            self.view.frame = rect;
            backgroundGradientView.alpha = 0.0f;
        }
                         completion:^(BOOL finished) {
                             [self.view removeFromSuperview];
                             [backgroundGradientView removeFromSuperview];
                             [self removeFromParentViewController];
                         }];
    }
    [self.delegate didHidePopoverController];
//THE PLACE I WANT TO CHANGE THE ALPHA BACK!
}

When you are showing the popup just assign ViewController instance as a delegate of ViewControllerB instance

The first way seems easy! But how to set the alpha back to 1 in a different class? That is what I`m asking for. — MasterRazer, Oct 14 '13 at 20:24
The second one should do it! Do you got any code to provide me or could you even make an example with my code? — MasterRazer, Oct 14 '13 at 20:25
in the first way you didn't need to set alpha back to 1 from different class, as viewDidAppear: will be in ViewController class and i think myBtn is the property of ViewController class. — Anshul Jain, Oct 15 '13 at 04:32
didn't work! I put a NSLOG in the "didHidePopOverController", but it is never called! :( Any suggestion? I've done everything like above! — MasterRazer, Oct 15 '13 at 12:22
can put NSLog before [self.delegate didHidePopoverController]; and print self.delegate. I guess delegate is null. Did you populate the delegate at the time of creation of ViewControllerB — Anshul Jain, Oct 15 '13 at 13:36
Solved it myself!! Here you go: http://stackoverflow.com/questions/11257848/update-a-label-through-button-from-different-view — MasterRazer, Oct 15 '13 at 17:36

score 0 · Answer 2 · edited May 23 '17 at 10:24

0

Update: I seached for it and found it. The awser from Anshul Join didn't worked for me but what worked for me was this: Update a label through button from different view

It is much less complicated and easy to implement. There are no delegates. Hope I could help anyone with this.

But summed up: Thanks to Anshul Jain for supporting me and trying to solve this for me. Thank you bro!

edited May 23 '17 at 10:24

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answered Oct 15 '13 at 17:39

MasterRazer

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Change UIButton alpha from different class

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