Animating the selection of UIButton - iphone

Question

Good Moscow evening to everyone!
I'm still unfamiliar with principles of iPhone animation (btw, does anybody know a big and nice tutorial on this?), but in my project I want to do button "highlighted-not highlighted" flicker to notify the user that its label has changed.
This code doesn't do anything (it's just a fragment of flicker animation):
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration: 0.5];
[button setHighlighted: YES];
[UIView commitAnimations];
And this one highlights the button, but does not do it in an animated form:
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration: 0.5];
[button setSelected: YES];
[UIView commitAnimations];
Can anyone help me and say:
What's wrong with this code?
What would fix the problem?
----------------------------------- UPDATE ------------------------------
I tried that kind of code, but it doesn't work either:
// ------------------------
// --- animation ----------
// ------------------------
- (void)animateIn
{
[UIView beginAnimations: #"animateIn" context:nil];
[UIView setAnimationDuration: 0.2];
[UIView setAnimationDelegate:self];
[UIView setAnimationDidStopSelector:#selector(animationDidStop:finished:context:)];
[control setBackgroundColor:[UIColor blackColor]];
[UIView commitAnimations];
}
- (void)animateOut
{
[UIView beginAnimations: #"animateOut" context:nil];
[UIView setAnimationDuration: 0.2];
[UIView setAnimationDelegate:self];
[UIView setAnimationDidStopSelector:#selector(animationDidStop:finished:context:)];
[control setBackgroundColor:[UIColor whiteColor]];
[UIView commitAnimations];
}
- (void)animationDidStop:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context
{
if([animationID isEqualToString: #"animateIn"])
{
[self animateOut];
return;
}
else if ([animationID isEqualToString: #"animateOut"])
{
cycleCount++;
if(cycleCount < 3)
[self animateIn];
else
cycleCount = 0;
return;
}
}
#end

Answer 1

//isFlickerOn is declared in .h file as BOOL isFlickerOn;
//flickerTimer is declared in .h file as NSTimer *flickerTimer;
//flickerCount is declared in .h file as int flickerCount;
//control is a UILabel, UIButton background color is really hard to notice
//especially the roundedRect UIButton, so I just flickered a UILabel's textColor
-(void)flickerOn {
if (flickerCount < 5)
{
flickerCount++;
if (!isFlickerOn)
{
[control setTextColor:[UIColor yellowColor]];
isFlickerOn = YES;
}
else
{
[control setTextColor:[UIColor blueColor]];
isFlickerOn = NO;
}
}
else
{
[flickerTimer invalidate];
}
}
-(void)flickerAnimation {
flickerCount = 0;
flickerTimer = [NSTimer scheduledTimerWithTimeInterval:0.3f target:self selector:#selector(flickerOn) userInfo:nil repeats:YES];
}

Answer 2

Not all attributes of a UIView are animatable - and I do not believe "highlighted" or "selected" are.
Typically, it's usable for non-boolean values, like "center", "alpha", "frame" and "bounds".
Try tweaking the alpha instead, and you'll see it will work.

Answer 3

You need to create a callback method that executes when the first animation finishes. You use that callback to do create a deselected animation. Keep in mind that there is no gradual "selection state" like there is for transparency. You have to use the
[UIView setAnimationDelegate:self];
[UIView setAnimationDidStopSelector:#selector(animationDidStop:finished:context:)];
[UIView beginAnimations:#"animateIn" context:NULL];
From Apple's docs:
- (void)animationDidStop:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context {
Your method must take the following arguments:
animationID
An NSString containing an optional application-supplied identifier. This is the identifier that is passed to the beginAnimations:context: method. This argument can be nil.
finished
An NSNumber object containing a Boolean value. The value is YES if the animation ran to completion before it stopped or NO if it did not.
context
An optional application-supplied context. This is the context data passed to the beginAnimations:context: method. This argument can be nil.
When the animation is finished, the callback animationDidStop is called and passed in the string #"animateIn". You can use that method to check which animation was called and handle that there.