Hide autolayout UIView : How to get existing NSLayoutConstraint to update this one

I just built this Category (https://github.com/damienromito/UIView-UpdateAutoLayoutConstraints) that update constrains when you want:

//you can use tools to hide/show a uiview
[myView1 hideByHeight:YES];

Or just do it to hide an UIView with autolayout:

//Hide View 
[myView1 setConstraintConstant:0 forAttribute:NSLayoutAttributeHeight];

UIView has a method that returns all constraints affecting its layout in one of the dimensions:

NSArray *constraints = 
[someView constraintsAffectingLayoutForAxis:UILayoutConstraintAxisVertical];

Then you can just find the one you're interested in.