UIView+Parallax.h

//
//  UIView+Parallax.h
//

#import <Foundation/Foundation.h>

@interface UIView (Parallax)
-(void)addBackgroundParallax:(CGFloat)strength;
-(void)addForegroundParallax:(CGFloat)strength;
-(void)removeParallax;
@end

UIView+Parallax.m

//
//  UIView+Parallax.m
//

#import <objc/runtime.h>
#import "UIView+Parallax.h"


@implementation UIView (Parallax)


-(void)addBackgroundParallax:(CGFloat)strength
{
  [self addParallax:-strength];
}


-(void)addForegroundParallax:(CGFloat)strength
{
  [self addParallax:strength];
}


-(void)removeParallax
{
  for (UIMotionEffect *effect in self.motionEffects) {
    [self removeMotionEffect:effect];
  }
}


-(void)addParallax:(CGFloat)amount
{
  [self removeParallax];

  UIInterpolatingMotionEffect *verticalMotionEffect = [[UIInterpolatingMotionEffect alloc] initWithKeyPath:@"center.y" type:UIInterpolatingMotionEffectTypeTiltAlongVerticalAxis];
  verticalMotionEffect.minimumRelativeValue = @(-amount);
  verticalMotionEffect.maximumRelativeValue = @(amount);

  UIInterpolatingMotionEffect *horizontalMotionEffect = [[UIInterpolatingMotionEffect alloc] initWithKeyPath:@"center.x" type:UIInterpolatingMotionEffectTypeTiltAlongHorizontalAxis];
  horizontalMotionEffect.minimumRelativeValue = @(-amount);
  horizontalMotionEffect.maximumRelativeValue = @(amount);

  UIMotionEffectGroup *group = [UIMotionEffectGroup new];
  group.motionEffects = @[horizontalMotionEffect, verticalMotionEffect];
  [self addMotionEffect:group];
}

@end

UIViewExtension.swift

//
//  UIViewExtension.swift
//

import Foundation
import UIKit

public extension UIView
{
    public func addBackgroundParallax(strength:CGFloat)
    {
        addParallax(-strength)
    }


    public func addForegroundParallax(strength:CGFloat)
    {
        addParallax(strength)
    }


    public func removeParallax()
    {
        if let effects: [UIMotionEffect] = self.motionEffects as? [UIMotionEffect]
        {
            for effect:UIMotionEffect in effects
            {
                removeMotionEffect(effect)
            }
        }
    }

    public func addParallax(amount:CGFloat)
    {
        removeParallax()

        var verticalMotionEffect:UIInterpolatingMotionEffect = UIInterpolatingMotionEffect(keyPath: "center.y", type: UIInterpolatingMotionEffectType.TiltAlongVerticalAxis)
        verticalMotionEffect.minimumRelativeValue = -amount
        verticalMotionEffect.maximumRelativeValue = amount

        var horizontalMotionEffect = UIInterpolatingMotionEffect(keyPath: "center.x", type: UIInterpolatingMotionEffectType.TiltAlongHorizontalAxis)
        horizontalMotionEffect.minimumRelativeValue = -amount
        horizontalMotionEffect.maximumRelativeValue = amount

        var group = UIMotionEffectGroup()
        group.motionEffects = [horizontalMotionEffect, verticalMotionEffect]
        self.addMotionEffect(group)
    }
}