UIView animated changes with auto layout constraints

Question

Say that I have a project which looks like the following: There are two `UIView`s - one called `yellowBox` and the other called `redBox`. The auto layout constraints dictate that the `yellowBox` is 60 points from the top of the superview with 350 points leading and trailing spaces (i.e. to left and right of the view). The `redBox` has the same leading and trailing space constraints. There is a vertical space constraint between the two boxes of 0 to indicate that the bottom of the `yellowBox` should always be directly on top of the `redBox`. When the user taps the Expand Yellow Box button, I would like the height of the `yellowBox` to increase and, as a result, the `redBox` moves down to continue satisfying the vertical space constraint (that the `yellowBox` is always on top of the `redBox`). Here is the animation code: ``` - (IBAction)expandYellowBox:(id)sender { [UIView animateWithDuration:0.5 animations:^{ CGRect newFrame = self.yellowBox.frame; newFrame.size.height += 50; self.yell…

Accepted Answer

Try it as mentioned by shwet-solanki, but add the following line after changing the constraint:

```
[self.view layoutIfNeeded];
```

the IBAction would look like:

```
- (IBAction)expandYellowBox:(id)sender {

[UIView animateWithDuration:0.5
                 animations:^{
                     self.yellowBoxHeightConstraint.constant += 50;
                     [self.view layoutIfNeeded];
                 }];
}
```

Where `yellowBoxHeightConstraint` is the `IBOutlet` for height constraint of `yellowBox`. Hope this helps.

UIView animated changes with auto layout constraints

Solution

Problem