How can I animate a box to expand and contract on touch?

Question

I read the intro to core animation from Apple, searched all over for 'ios tweening,' 'ios easing,' and related thins but surprisingly came up empty handed.

How can I make my UILabel contract and hide its subview buttons while keeping the UILabel showing? Links, code, design overview, or anything that gets this done will be extremely helpful.

Answer 1

Surprised no one stepped to this, the answer is pretty straightforward. But maybe that's why.

I'm not sure about animating the UILabel itself, though as it is a subclass of UIView, I suspect it would be fairly normal.

The simplest way to get this done is to use the UIView static method:

+ (void)animateWithDuration:(NSTimeInterval)duration 
                 animations:(void (^)(void))animations

In my case, I have a UILabel, myLabel on top of a UIView myContainer with a UIButton dismissButton. Presuming I want dismissButton, when clicked, to roll up myContainer I would Crtl-drag my dismissButton button to the proper viewController.m and in the -(IBAction) method write:

-(IBAction)dismissButtonPressed:(id)sender
{
   [UIView animateWithDuration:1.0
                    animations:^{ 
           [self.myContainer.frame = CGRectMake(0,0,frame.bounds.size.width,20)];
           [self.dismissButton removeFromSuperView]; }];
}

Note: This is from my limited memory, so point out any errors.

Note2: If you are using this to help yourself, watch those semicolons, brackets and braces

Now, most people reading this for reference might want more functionality that clicking a button which rolls up a view forever. There are more detailed animateWith* methods.

There is

+(void)animateWithDuration:(NSTimeInterval)duration animations:(void (^)(void))animations completion:(void (^)(BOOL finished))completion

which allows a completion block to be done once the view is finished animating. Note from Paul Hegarty's iOS class: You may call more animate methods from your completion block.

There is another animation method that lets us specify animation options.

+ (void)animateWithDuration:(NSTimeInterval)duration delay:(NSTimeInterval)delay options:(UIViewAnimationOptions)options animations:(void (^)(void))animations completion:(void (^)(BOOL finished))completion

The options include:

enum {
   UIViewAnimationOptionLayoutSubviews            = 1 <<  0,
   UIViewAnimationOptionAllowUserInteraction      = 1 <<  1,
   UIViewAnimationOptionBeginFromCurrentState     = 1 <<  2,
   UIViewAnimationOptionRepeat                    = 1 <<  3,
   UIViewAnimationOptionAutoreverse               = 1 <<  4,
   UIViewAnimationOptionOverrideInheritedDuration = 1 <<  5,
   UIViewAnimationOptionOverrideInheritedCurve    = 1 <<  6,
   UIViewAnimationOptionAllowAnimatedContent      = 1 <<  7,
   UIViewAnimationOptionShowHideTransitionViews   = 1 <<  8,

   UIViewAnimationOptionCurveEaseInOut            = 0 << 16,
   UIViewAnimationOptionCurveEaseIn               = 1 << 16,
   UIViewAnimationOptionCurveEaseOut              = 2 << 16,
   UIViewAnimationOptionCurveLinear               = 3 << 16,

   UIViewAnimationOptionTransitionNone            = 0 << 20,
   UIViewAnimationOptionTransitionFlipFromLeft    = 1 << 20,
   UIViewAnimationOptionTransitionFlipFromRight   = 2 << 20,
   UIViewAnimationOptionTransitionCurlUp          = 3 << 20,
   UIViewAnimationOptionTransitionCurlDown        = 4 << 20,
   UIViewAnimationOptionTransitionCrossDissolve   = 5 << 20,
   UIViewAnimationOptionTransitionFlipFromTop     = 6 << 20,
   UIViewAnimationOptionTransitionFlipFromBottom  = 7 << 20,
};
typedef NSUInteger UIViewAnimationOptions;

Hopefully someone can benefit from this long winded intro to animating a UIView.