UIImage resizes unexpectedly - ios

Question

I have View Controller inside the View Controller I have placed a UIImageView I am trying to draw on the image present in the UIImageView in this manner.
- (void)viewDidLoad {
[super viewDidLoad];
[self.drawImageView setImage:editableImage];
UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(drawingViewDidPan:)];
panGesture.maximumNumberOfTouches = 1;
self.drawImageView.userInteractionEnabled = YES;
[self.drawImageView addGestureRecognizer:panGesture];
}
Where drawImageView is my UIImageView and editableImage is the UIImage I am trying to draw on.
I am implementing the drawing part as follows
- (void)drawingViewDidPan:(UIPanGestureRecognizer*)sender
{
CGPoint currentDraggingPosition = [sender locationInView:drawImageView];
if(sender.state == UIGestureRecognizerStateBegan){
prevDraggingPosition = currentDraggingPosition;
}
if(sender.state != UIGestureRecognizerStateEnded){
[self drawLine:prevDraggingPosition to:currentDraggingPosition];
}
prevDraggingPosition = currentDraggingPosition;
}
-(void)drawLine:(CGPoint)from to:(CGPoint)to
{
CGSize size = drawImageView.frame.size;
UIGraphicsBeginImageContextWithOptions(size, NO, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
[drawImageView.image drawAtPoint:CGPointZero];
CGFloat strokeWidth = 5.0;
UIColor *strokeColor = [UIColor redColor];
CGContextSetLineWidth(context, strokeWidth);
CGContextSetStrokeColorWithColor(context, strokeColor.CGColor);
CGContextSetLineCap(context, kCGLineCapRound);
CGContextMoveToPoint(context, from.x, from.y);
CGContextAddLineToPoint(context, to.x, to.y);
CGContextStrokePath(context);
drawImageView.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
The problem is as soon as I place my finger to draw the UIImage resizes and becomes small rest all works good
How can I solve this ?
My editableImage is coming from another viewcontroller which has a button called draw
-(IBAction)drawOnOmage:(id)sender {
[self performSegueWithIdentifier:#"MySegue1" sender:self];
}
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
ThirdViewController *destinationController = (ThirdViewController *)segue.destinationViewController;
destinationController->editableImage = self.editImage.image;
}

Answer 1

I just copied your code to a new project and it seems to work for me. The only thing I notice is that you are not using a #property declaration for prevDraggingPosition - maybe this is the problem? Can you show us how you declare prevDraggingPosition?
Have a look at my example (that works for me, I only added self.):
#import "ViewController.h"
#interface ViewController ()
#property (nonatomic, strong) IBOutlet UIImageView *drawImageView;
#property (nonatomic, assign) CGPoint prevDraggingPosition;
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(drawingViewDidPan:)];
panGesture.maximumNumberOfTouches = 1;
self.drawImageView.userInteractionEnabled = YES;
[self.drawImageView addGestureRecognizer:panGesture];
}
- (void)drawingViewDidPan:(UIPanGestureRecognizer*)sender
{
CGPoint currentDraggingPosition = [sender locationInView:self.drawImageView];
if(sender.state == UIGestureRecognizerStateBegan){
self.prevDraggingPosition = currentDraggingPosition;
}
if(sender.state != UIGestureRecognizerStateEnded){
[self drawLine:self.prevDraggingPosition to:currentDraggingPosition];
}
self.prevDraggingPosition = currentDraggingPosition;
}
-(void)drawLine:(CGPoint)from to:(CGPoint)to
{
CGSize size = self.drawImageView.frame.size;
UIGraphicsBeginImageContextWithOptions(size, NO, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
[self.drawImageView.image drawAtPoint:CGPointZero];
CGFloat strokeWidth = 5.0;
UIColor *strokeColor = [UIColor redColor];
CGContextSetLineWidth(context, strokeWidth);
CGContextSetStrokeColorWithColor(context, strokeColor.CGColor);
CGContextSetLineCap(context, kCGLineCapRound);
CGContextMoveToPoint(context, from.x, from.y);
CGContextAddLineToPoint(context, to.x, to.y);
CGContextStrokePath(context);
self.drawImageView.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
#end