以编程方式更改Y位置约束

Question

This is four button open new view between them.

I set constraints through Xcode, and want to change position programatically, but it does not work. I am new, kindly help. I used

[_btn_patientInformation.translatesAutoresizingMaskIntoConstraints: NO];
NSLayoutConstraint *constraintCoordinatesCenterY =[NSLayoutConstraint                                                  constraintWithItem:_btn_patientInformation attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:coordinatesView attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:1];

But unfortunately it does not work.

Answer 1

Use outlet for the constraint you want to change.

The outlet will be looking like this:

 @property (weak, nonatomic) IBOutlet NSLayoutConstraint * topPositionConstraint;

Connect the above constraint to the Y constraint in storyboard.

And to change the constraint, you can simply do:

  topPositionConstraint.constant=yourValue;

and dont forget to call

    [self.view layoutIfNeeded];

after the change in constraints.

Try to set the constraints this way:

• Select the top button, and give leading,trailing,top,height,width constraint.

• Now select the second button, and ctrl drag it to first button, and release the mouse click, and select vertical spacing and leading constraint.

• Do the same for the third button,except you ctrl drag the third button to the second button.

Now to move all these buttons up or down , you can simply change the top constraint for the first button.