- (void)viewDidLoad {
[super viewDidLoad];
[self initPathLayer];
[self initHandleView];
[self initHandlePanGestureRecognizer];
}


- (void)initPathLayer {
pathLayer_ = [CAShapeLayer layer];
pathLayer_.lineWidth = 1;
pathLayer_.fillColor = nil;
pathLayer_.strokeColor = [UIColor lightGrayColor].CGColor;
pathLayer_.lineCap = kCALineCapButt;
pathLayer_.lineJoin = kCALineJoinRound;
pathLayer_.frame = self.view.bounds;
pathLayerCenter_ = CGPointMake(CGRectGetMidX(pathLayer_.frame), CGRectGetMidY(pathLayer_.frame));
[self.view.layer addSublayer:pathLayer_];
}


- (void)initHandleView {
handlePathPointIndex_ = 0;
CGRect rect = CGRectMake(0, 0, 30, 30);
CAShapeLayer *circleLayer = [CAShapeLayer layer];
circleLayer.fillColor = [UIColor redColor].CGColor;
circleLayer.strokeColor = [UIColor redColor].CGColor;
circleLayer.lineWidth = 2;
UIBezierPath *circlePath = [UIBezierPath bezierPathWithOvalInRect:CGRectInset(rect, circleLayer.lineWidth, circleLayer.lineWidth)];
circleLayer.frame = rect;
circleLayer.path = circlePath.CGPath;
handleView_ = [[UIView alloc] initWithFrame:rect];

CGRect lineRect = CGRectMake(0,0,CGRectGetMaxX([[UIScreen mainScreen] bounds]), CGRectGetMaxY([[UIScreen mainScreen] bounds]));
CGPoint center = CGPointMake(CGRectGetMidX(pathLayer_.frame), CGRectGetMidY(pathLayer_.frame));
lineView_ = [[UIView alloc] initWithFrame:lineRect];
CAShapeLayer *lineLayer = [CAShapeLayer layer];
lineLayer.fillColor = [UIColor blueColor].CGColor;
lineLayer.strokeColor = [UIColor blueColor].CGColor;
lineLayer.lineWidth = 2;
lineLayer.frame = self.view.bounds;
UIBezierPath *linePath = [UIBezierPath bezierPath];
CGPoint circlePoint = CGPointMake(handleView_.center.x, handleView_.center.y);
[linePath moveToPoint:center]; //Center
[linePath addLineToPoint:circlePoint];
[linePath moveToPoint:circlePoint]; //Handle
lineLayer.path = linePath.CGPath;

[handleView_.layer insertSublayer:circleLayer above:handleView_.layer];
[handleView_.layer insertSublayer:lineLayer above:handleView_.layer];
//  handleView_.layer.masksToBounds = YES;
float direction = DEGREES_TO_RADIANS(10);

CGAffineTransform rotationTransform = CGAffineTransformMakeRotation(direction);
[handleView_ setTransform:rotationTransform];


[self.view addSubview:lineView_];
[self.view addSubview:handleView_];

}

- (void)handleWasPanned:(UIPanGestureRecognizer *)recognizer {
switch (recognizer.state) {
    case UIGestureRecognizerStateBegan: {
        desiredHandleCenter_ = handleView_.center;
        break;
    }

    case UIGestureRecognizerStateChanged:
    case UIGestureRecognizerStateEnded:
    case UIGestureRecognizerStateCancelled: {
        CGPoint translation = [recognizer translationInView:self.view];
        desiredHandleCenter_.x += translation.x;
        desiredHandleCenter_.y += translation.y;
        [self moveHandleTowardPointAndRotateLine:desiredHandleCenter_];
        break;
    }

    default:
        break;
}

[recognizer setTranslation:CGPointZero inView:self.view];
}

- (void)moveHandleTowardPointAndRotateLine:(CGPoint)point {
CGFloat earlierDistance = [self distanceToPoint:point ifHandleMovesByOffset:-1];
CGFloat currentDistance = [self distanceToPoint:point ifHandleMovesByOffset:0];
CGFloat laterDistance = [self distanceToPoint:point ifHandleMovesByOffset:1];
if (currentDistance <= earlierDistance && currentDistance <= laterDistance)
    return;

NSInteger step;
CGFloat distance;
if (earlierDistance < laterDistance) {
    step = -1;
    distance = earlierDistance;
} else {
    step = 1;
    distance = laterDistance;
}

NSInteger offset = step;
while (true) {
    NSInteger nextOffset = offset + step;
    CGFloat nextDistance = [self distanceToPoint:point ifHandleMovesByOffset:nextOffset];
    if (nextDistance >= distance)
        break;
    distance = nextDistance;
    offset = nextOffset;
}
handlePathPointIndex_ += offset;

// Make one end of the line move with handle (point) while the other is pinned to center of pathLayer_ (ie. in figure8 its the cross point, in a circle it's center)

//CGFloat rot = [self getTouchAngle:point];
CGFloat rot = atan2f((point.x - pathLayerCenter_.x), -(point.y - pathLayerCenter_.y));
handleView_.layer.transform = CATransform3DMakeRotation(rot, 0., 0., 1.);
[self layoutHandleView];
}