Use of beginAnimations discouraged

Question

I was informed recently by meronix that use of beginAnimations is discouraged. Reading through the UIView class reference I see that this is indeed true - according to the Apple class ref:

Use of this method is discouraged in iOS 4.0 and later. You should use the block-based animation methods to specify your animations instead.

I see that a large number of other methods - which I use frequently - are also "discouraged" which means they'll be around for iOS 6 (hopefully) but probably will be deprecated/removed eventually.

Why are these methods being discouraged?

As a side note, right now I'm using beginAnimations in all sorts of apps, most commonly to move the view up when a keyboard is shown.

//Pushes the view up if one of the table forms is selected for editing
- (void) keyboardDidShow:(NSNotification *)aNotification
{
    if ([isRaised boolValue] == NO)
    {
        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDuration:0.25];
        self.view.center = CGPointMake(self.view.center.x, self.view.center.y-moveAmount);
        [UIView commitAnimations];
        isRaised = [NSNumber numberWithBool:YES];
    }
}

Not sure how to duplicate this functionality with block-based methods; a tutorial link would be nice.

Answer 1

They are discouraged because there is a better, cleaner alternative

In this case all a block animation does is automatically wrap your animation changes (setCenter: for example) in begin and commit calls so you dont forget. It also provides a completion block, which means you don't have to deal with delegate methods.

Apple's documentation on this is very good but as an example, to do the same animation in block form it would be

[UIView animateWithDuration:0.25 animations:^{
    self.view.center = CGPointMake(self.view.center.x, self.view.center.y-moveAmount);
} completion:^(BOOL finished){
}];

Also ray wenderlich has a good post on block animations: link

Another way is to think about a possible implementation of block animations

+ (void)animateWithDuration:(NSTimeInterval)duration animations:(void (^)(void))animations
{
    [UIView beginAnimations];
    [UIView setAnimationDuration:duration];
    animations();
    [UIView commitAnimations];
}

Answer 2

Check out this method on UIView, which makes it quite simple. The trickiest part nowadays is not allowing a block to have a strong pointer to self:

//Pushes the view up if one of the table forms is selected for editing
- (void) keyboardDidShow:(NSNotification *)aNotification
{
  if ([isRaised boolValue] == NO)
  {
    __block UIView *myView = self.view;
    [UIView animateWithDuration:0.25 animations:^(){
      myView.center = CGPointMake(self.view.center.x, self.view.center.y-moveAmount);
     }];
    isRaised = [NSNumber numberWithBool:YES];
  }
}