How to change constraints programmatically that is added from storyboard?

Question

I have one screen. It will display like below

Now When User clicked I have an Account and Password(button) it will display like below

I want to move both views accordingly I added constraints using storyboard.Now need to change constraints from programming..

Memento

Just create an outlet of the constraint you want to change like you create outlet of UIButton or UILabel. – Inly

Answer 1

You need to create an IBOutlet of your constraint.

Then you set the constant value of your constraint in code:

labelWidthConstraint.constant = newValue

If you want it animated you can do something like this:

Swift

labelWidthConstraint.constant = newValue
UIView.animate(withDuration: 0.3, animations: { 
    self.view.layoutIfNeeded()
})

Objective-C

self.labelWidthConstraint.constant = newValue;
[UIView animateWithDuration:0.3 animations:^{        
    [self.view layoutIfNeeded];
}];

Midis

You should not call layoutSubviews()(see docs). Use layoutIfNeeded() instead. – Cain

Nilam Pari, I updated the answer to contain an Objective-C example. – Midis

Also, for animation, you don't need the constant to be set inside animation block. Put it outside of the animation block, so animation block has layoutIfNeeded method only. – Vietnamese

Would be nice to show example that doesn't use hard coded values - how does the UI look different on a 4s in comparison to a 7s plus? – Jehol