zapsleep

#pragma mark - Gyroscope to offset
         
- (CGPoint)contentOffsetWithRotationRate:(CMRotationRate)rotationRate {
    double xOffset = (fabs(rotationRate.y) > DV_ROTATION_THRESHOLD)?rotationRate.y*DV_ROTATION_MULTIPLIER:0.f;
    double yOffset = (fabs(rotationRate.x) > DV_ROTATION_THRESHOLD)?rotationRate.x*DV_ROTATION_MULTIPLIER:0.f;
    CGPoint newOffset = CGPointMake(self.contentOffset.x + xOffset,
                                    self.contentOffset.y + yOffset);
    return newOffset;
}
                        

zapsleep

-(void)setGyroscopeControl:(BOOL)gyroscopeControl {
    if (_gyroscopeControl == gyroscopeControl)
        return;
    
    _gyroscopeControl = gyroscopeControl;
    
    if (gyroscopeControl) {
        [self.motionManager startDeviceMotionUpdates];
        [self.displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    } else {

zapsleep

-(CADisplayLink *)displayLink {
    if (!_displayLink) {
        _displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(displayLinkHandler)];
    }
    
    return _displayLink;
}

-(CMMotionManager *)motionManager {
    if (!_motionManager) {

zapsleep

-(DVParallaxView *)parallaxView {
    if (!_parallaxView) {
        _parallaxView = [[DVParallaxView alloc] initWithFrame:self.view.bounds];
        [_parallaxView setBackgroundImage:[UIImage imageNamed:@"galaxy2"]];
        
        UIImageView *earth = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"earth"]];
        earth.frame = (CGRect) {.origin = CGPointMake(CGRectGetMidX(self.view.bounds) - earth.image.size.width/2.f,
                                                      CGRectGetMidY(self.view.bounds) - earth.image.size.height/2.f),
                                .size = earth.frame.size};
        [_parallaxView addSubview:earth];

zapsleep

#pragma mark - Getters

-(UIImageView *)backgroundImageView {
    if (!_backgroundImageView) {
        _backgroundImageView = [[UIImageView alloc] init];
        _backgroundImageView.contentMode = UIViewContentModeCenter;
        _backgroundImageView.center = CGPointMake(CGRectGetMidX(self.bounds),
                                                  CGRectGetMidY(self.bounds));
    }
    

zapsleep

-(void)setContentOffset:(CGPoint)contentOffset {
    BOOL backgroundReachedEdgeX = NO;
    BOOL backgroundReachedEdgeY = NO;
    double contentDivider;

    //1
    if (self.backgroundImageView) {
        contentDivider = self.subviews.count*self.parallaxDistanceFactor;
        CGPoint newCenter = CGPointMake(self.backgroundImageView.center.x + (contentOffset.x - _contentOffset.x)/contentDivider,
                                        self.backgroundImageView.center.y - (contentOffset.y - _contentOffset.y)/contentDivider);

zapsleep

#pragma mark - Gesture handler

- (void)panHandler:(UIPanGestureRecognizer *)pan {
    CGPoint translation = [pan translationInView:self];
    [self setContentOffset:CGPointMake(self.contentOffset.x + translation.x,
                                       self.contentOffset.y - translation.y)];
    
    [pan setTranslation:CGPointZero inView:self];
}

zapsleep

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        self.parallaxDistanceFactor = 2.f;
        self.parallaxFrontFactor = 20.f;
        self.backgroundColor = [UIColor clearColor];
        [self addSubview:self.backgroundImageView];
        
        UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panHandler:)];

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@interface DVParallaxView()
@property (nonatomic, strong) UIImageView *backgroundImageView;
@end

zapsleep

#import <UIKit/UIKit.h>

@interface DVParallaxView : UIView

@property (nonatomic, strong) UIImage *backgroundImage;
@property (nonatomic, strong) UIView *frontView;
@property (nonatomic) float parallaxDistanceFactor;
@property (nonatomic) float parallaxFrontFactor;
@property (nonatomic) CGPoint contentOffset;