AnimateWithDuration无法正常工作

Question

I'm trying to run an example to test this function. I have a label an a button in the storyBoard and I have referenced the bottom constraint of the label in the view controller. When I use the button I want the label to move with an animation but it moves without it. Here's the code of the button:

- (IBAction)sd:(id)sender {
[UIView animateWithDuration:0.5f animations:^{
    self.constraint.constant += 50;
}];
}

I know how to use it in swift but I'm having problems in objective c and I know it will be just for a little mistake... Any help?

Answer 1

This is not the right way of animating a UI component constrained with Autolayout. You should first update the constraint, then call layoutIfNeeded within the animation block:

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

Answer 2

Use this

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

Answer 3

Try this setNeedsLayout helps in some cases.

self.constraint.constant += 50;
[UIView animateWithDuration:0.5f
                 animations:^{
                      [self.view setNeedsLayout];
                  }
                  completion:^(BOOL finished) {

                  }];