Adding autolayout constraints programatically on presenting ViewController - ios

Question

I m presenting a viewcontroller like a popup from my mainviewcontroller on iPad which works fine. But currently I’m setting its prefferedContentSize to fit on screen so when I rotate the size is not autoresized. I need the popupview to be center aligned to the mainviewcontroller with width 97% and height 90% in portrait and landscape. So I’m now trying to add autolayout constraint on my popupViewController but not sure how. Below is the code that I’ve tried so far. This gives me an 'NSInternalInconsistencyException' error
#import "ViewController.h"
#interface ViewController ()
{
PopUpViewController *popUpController;
}
#end
- (IBAction)showPopUp:(UIButton *)sender {
popUpController = [[PopUpViewController alloc]initWithNibName:#"PopUpViewController" bundle:nil];
popUpController.view.center = self.view.center;
popUpController.view.layer.cornerRadius = 8.0f;
popUpController.view.layer.masksToBounds = YES;
popUpController.view.layer.borderWidth = 1.0f;
popUpController.view.layer.borderColor = [UIColor blueColor].CGColor;
popUpController.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
popUpController.modalPresentationStyle = UIModalPresentationFormSheet;
// CGPoint frameSize = CGPointMake([[UIScreen mainScreen] bounds].size.width*0.97f, [[UIScreen mainScreen] bounds].size.height*0.9f);
// popUpController.preferredContentSize = CGSizeMake(frameSize.x, frameSize.y);
[self addConstraint];
[self.navigationController presentViewController:popUpController animated:YES completion:nil];
}
-(void)addConstraint
{
// Width constraint, half of parent view width
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:popUpController.view.superview
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeWidth
multiplier:0.97
constant:0]];
// Height constraint, half of parent view height
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:popUpController.view.superview
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeHeight
multiplier:0.9
constant:0]];
// Center horizontally
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:popUpController.view.superview
attribute:NSLayoutAttributeCenterX
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeCenterX
multiplier:1.0
constant:0.0]];
// Center vertically
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:popUpController.view.superview
attribute:NSLayoutAttributeCenterY
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeCenterY
multiplier:1.0
constant:0.0]];
}

Answer 1

In your storyboard, link your constraint to a controller property. Then, to change your constraint value: self.myConstraint.constant = 0;.
Also, call layoutIfNeeded on your view(s) after changing your constraints values, do it inside a UIAnimation.
Easiest way to manage constraints.