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

I know how to modify a existing constraint. But I would to know if someone has found a solution to get a constraint without save this one as a property.

Current solution to set Constraint height:

1) save NSLayoutConstraint in a variable:

NSLayoutConstraint *heightConstraint = [NSLayoutConstraint constraintWithItem:myView
                                                                    attribute:NSLayoutAttributeHeight
                                                                    relatedBy:NSLayoutRelationEqual
                                                                       toItem:nil
                                                                    attribute:NSLayoutAttributeNotAnAttribute
                                                                   multiplier:1.0f
                                                                     constant:20];
[self.view addConstraint:heightConstraint];

2) Set the constant of the Constraint saved to "0.0" ( to hide this view)

[heightConstraint setConstant:200];

I'm looking for a solution like this:

 [myView setConstraint:@"0." forAttribute:NSLayoutAttributeHeight]
like image 849
Damien Romito Avatar asked Mar 13 '14 16:03

Damien Romito


2 Answers

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];

enter image description here

Or just do it to hide an UIView with autolayout:

//Hide View 
[myView1 setConstraintConstant:0 forAttribute:NSLayoutAttributeHeight];
like image 163
Damien Romito Avatar answered Oct 23 '22 22:10

Damien Romito


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.

like image 26
DrummerB Avatar answered Oct 23 '22 22:10

DrummerB