Draw Line in UIImageView by using CGPoints

Question

I have an imageView and i want to draw lines on image in that imageView using CGPoints but i am getting errors like: invalid context etc.. any solution to draw lines without CGContext approach.

CGContextRef cntxt = UIGraphicsGetCurrentContext(); CGContextMoveToPoint(cntxt, p1.x, p1.y); CGContextAddLineToPoint(cntxt, p2.x, p2.y); CGContextStrokePath(cntxt);

Thanks

Rob Napier · Accepted Answer · 2012-05-31 21:09:54Z

1

You are likely attempting to draw outside of drawRect:. If you check the value of cntxt, it is likely NULL. A draw context is created prior to calling drawRect: and is destroyed afterwards. There is generally no "current context" outside of this function.

You need to keep track of your points in a data structure. In drawRect:, you will then do whatever drawing you need to do based on that data.

answered May 31, 2012 at 21:09

Rob Napier

301k37 gold badges492 silver badges660 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Dani Over a year ago

yes i am not using drawRect method as i am doing this in UIViewController subclass. drawRect method is available in UIView subclass

Rob Napier Over a year ago

UIViewController can't draw anything at all. It's not a view. Your view controller should generally hold onto the relevant data, and pass it to the view for drawing.

Dani Over a year ago

Thanks Rob I did it in a UIView class and i got what i wanted.. :)

Collectives™ on Stack Overflow

Draw Line in UIImageView by using CGPoints

1 Answer 1

3 Comments

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Related