如何在不影响背景图像的情况下在UIImageView上绘制？

Question

I have single view controller application. It contains UIImageView and on user touch it draws on the screen. This part works fine. In view did load method of viewcontroller I set up a different image as background image. And I set that image view background as clear color. Now when I try to erase something from UIImageView, i also erase the view controller background view. How can I avoid this ?

Here is my code To set an background for viewcontroller in viewDidLoad()

self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"bacground.png"]];
image.backgroundColor = [UIColor clearColor];    

To draw on screen in touchesMoved method

UIGraphicsBeginImageContext(image.frame.size);
[image.image drawInRect:CGRectMake(0, 0, image.frame.size.width, image.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), lineWidth);
CGContextSetStrokeColorWithColor(UIGraphicsGetCurrentContext(), self.drawcolor.CGColor);
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
image.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

To erase I am just setting drawcolor to whiteColor.

Answer 1

To set the image for background use following and then try to draw the other image on view

            UIImageView *background = [[UIImageView alloc]initWithImage:[UIImage imageNamed: @"backipad.png"]];
self.view = background;

Try with above, I have not came across such problem ever but I think this will work for you..and

 background.userInteractionEnabled = YES;