How to position activity indicator to the center of its superview using Auto Layout programmatically?

Question

Why the following code does not work for positioning activity indicator to the center of its superview:

UIActivityIndicatorView *activityIndicator = [[UIActivity         


        

Answer 1

It's meeting it's requirements by being in the corner, since you're not stating that the gaps on each side have to be the same. Try this instead:

[self.superview addConstraint:[NSLayoutConstraint constraintWithItem:activityIndicator
               attribute:NSLayoutAttributeCenterX 
               relatedBy:NSLayoutRelationEqual 
                  toItem:self.superview 
               attribute:NSLayoutAttributeCenterX 
              multiplier:1.0 
                constant:0.0]];

And to center vertically do this too:

[self.superview addConstraint:[NSLayoutConstraint constraintWithItem:activityIndicator
               attribute:NSLayoutAttributeCenterY 
               relatedBy:NSLayoutRelationEqual 
                  toItem:self.superview 
               attribute:NSLayoutAttributeCenterY 
              multiplier:1.0 
                constant:0.0]];

Alternatively, I highly recommend using the FLKAutoLayout project to simplify all this:

https://github.com/dkduck/FLKAutoLayout

Then you can do:

[activityIndicator alignCenterXWithView:self.superview predicate:nil];
[activityIndicator alignCenterYWithView:self.superview predicate:nil];

Which is nice :)