Animate the enabling of a UIBarButtonItem?

Question

Is there a way to animate enabling or disabling a button? I've tried the following with no success. I'm guessing at this point that the enabled property cannot be animated like opacity can – but I hope I'm wrong.

    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:1.0f];
    theButton.enabled = YES;
    [UIView setAnimationDelegate:self];
    [UIView commitAnimations];

I can't believe there isn't a setEnabled:(BOOL)enabled animated:(BOOL)animated method.

Answer 1

Animatable properties (through UIView beginAnimations:context:) are: frame, bounds, center, transform, alpha (from Apple docs).

So you've to determine what exactly your animation is (in terms of color/alpha/transform animations) and create manual animation (maybe you'll have to use CAAnimation instead of UIView beginAnimations:context:)

Answer 2

This is actually really easy. UIView.transitionWithView can take a snapshot of any view and cross-dissolve from the snapshot to the new state of the view. You can use that capability to animate a lot of changes, including enabled.

Just use the View Controller's view as the target view, specify TransitionCrossDissolve, then animate as you would normally.

UIView.transitionWithView(self.view,
    duration: 0.5,
    options: UIViewAnimationOptions.TransitionCrossDissolve,
    animations: { () -> Void in
        self.someButton.enabled = !self.someButton.enabled
}, completion:nil)

Answer 3

You can break down the enable/disable of a button into a change in opacity between two overlapping images each in one state or the other (i.e. make it look like a fade-in/fade-out). In the animation completion handler you can to do the actual enable/disable toggle.

Answer 4

Here's an idea :)

Within your animation block, Remove the button from view and add it again with disabled state. You can specify what kinda animation you want here..

Answer 5

Set: self.buttonSetEvent.customView.alpha = 0.2;

and try this

    CGContextRef context = UIGraphicsGetCurrentContext();
[UIView beginAnimations:nil context:context];
[UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
[UIView setAnimationDuration:0.15];
[UIView setAnimationRepeatCount:2];
[UIView setAnimationRepeatAutoreverses:YES];

self.buttonSetEvent.customView.alpha = 1;

[UIView setAnimationDelegate:self];
[UIView commitAnimations];