Question

When increasing the height of label, everything is fine and smooth. When decreaseing, the label is instantly changing the size then repositioning with animation.

@interface
@property (nonatomic, retain) IBOutlet UILabel *explanationLabel;

@implementation
CGRect frmExpl = explanationLabel.frame;
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:0.75];

frmExpl.size.height -= height;
explanationLabel.frame = frmExpl;

[UIView commitAnimations];  

I’ve tried replacing UILabel with UIView and of course there is no such problem with UIView.

Is there any special way to animate UILabel size decrease?

Here is a minimal project demonstrating the issue described. Download

Answer 1

I think what you are wanting to change is the bounds, rather than the frame. From the docs:

“The bounds rectangle determines the origin and scale in the view’s coordinate system within its frame rectangle and is measured in points. Setting this property changes the value of the frame property accordingly.” – UIView Class; bounds property

Try something like:

- (void)animate:(id)sender
{
    ...
    CGRect newBounds = testLabel.bounds;
    newBounds.size.height += 50;
    testLabel.bounds = newBounds;
    ...
}