How can I center a UIView programmatically on top of an existing UIView using Autolayout?

Question

In case of a successful Foursquare checkin, my iPhone app shows adds a view on top of the view which is shown.

I want the view to be centered on the X and Y and for

Answer 1

Try this:

NSLayoutConstraint *xCenterConstraint = [NSLayoutConstraint constraintWithItem:view1 attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:view2 attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0];
[superview addConstraint:xCenterConstraint];

NSLayoutConstraint *yCenterConstraint = [NSLayoutConstraint constraintWithItem:view1 attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:view2 attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0];
[superview addConstraint:yCenterConstraint];

Updated for Swift:

NSLayoutConstraint(item: view1, attribute: .centerX, relatedBy: .equal, toItem: view2, attribute: .centerX, multiplier: 1, constant: 0).isActive = true

NSLayoutConstraint(item: view1, attribute: .centerY, relatedBy: .equal, toItem: view2, attribute: .centerY, multiplier: 1, constant: 0).isActive = true