Update Multiplier

ViewController.h

#import <UIKit/UIKit.h>

#import “NSLayoutConstraint+Multiplier.h”

@interface ViewController : UIViewController

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

@end

ViewController.m

#import “ViewController.h”

@interface ViewController ()

@end

@implementation ViewController

– (void)viewDidLoad {

    [super viewDidLoad];

    

//    _layoutConstraintViewHeight.constant = 100;

    

    self.layoutConstraintViewHeight = [self.layoutConstraintViewHeight updateMultiplier:0.5];

    // Do any additional setup after loading the view, typically from a nib.

}

– (void)didReceiveMemoryWarning {

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

@end

NSLayoutConstraint+Multiplier.h

#import <UIKit/UIKit.h>

@interface NSLayoutConstraint (Multiplier)

-(instancetype)updateMultiplier:(CGFloat)multiplier;

@end

NSLayoutConstraint+Multiplier.m

#import “NSLayoutConstraint+Multiplier.h”

@implementation NSLayoutConstraint (Multiplier)

-(instancetype)updateMultiplier:(CGFloat)multiplier {

    NSLayoutConstraint *newConstraint = [NSLayoutConstraint constraintWithItem:self.firstItem attribute:self.firstAttribute relatedBy:self.relation toItem:self.secondItem attribute:self.secondAttribute multiplier:multiplier constant:self.constant];

    [newConstraint setPriority:self.priority];

    newConstraint.shouldBeArchived = self.shouldBeArchived;

    newConstraint.identifier = self.identifier;

    newConstraint.active = true;

    

    [NSLayoutConstraint deactivateConstraints:[NSArray arrayWithObjects:self, nil]];

    [NSLayoutConstraint activateConstraints:[NSArray arrayWithObjects:newConstraint, nil]];

    //NSLayoutConstraint.activateConstraints([newConstraint])

    return newConstraint;

}

@end

Download Sample Project From Github