R – iPhone image distortion

cocoa-touchiphonequartz-graphics

Are there any reasons why the simulator will display UIImageViews properly, but incorrectly on the iPhone?

My Process:
An image in a PNG file
Start a UIGraphicsBeginImageContext()
Draw the PNG in a CGrect
Draw text in the CGRect
Create an UIImage from the context
Set the image of a UIImaveView to the UIImage
Set the frame of the UIImageView to the size of the PNG
Add as a subview

Outcome:
The image does not display correctly. The rightmost 1-3 pixels of the image is just a vertical white line. This occurs only on the device and not on the simulator. I can fix the problem, but only by increasing the size of the UIImageView. If I increase the size.height of the UIImageView by 1 pixel, it displays the UIImage correctly. Of course, these leaves the iPhone to scale my image before drawing it on screen which is not desirable.

Any ideas why this occurs or any fixes for it?
(I will post my code if needed)

Best Answer

Here is the code to take my PNG file, draw it with text, and save as a UIImage. This image is then set to the image property of a UIImageView, whose frame is the size of the image (25x25).

-(UIImage *) elementImageWithFrame: (CGRect) aFrame image: (NSString *) anImage{


        int smallFontSize=FONT_SMALL;
        int largeFontSize=FONT_LARGE;

        CGSize mySize = aFrame.size;

        UIGraphicsBeginImageContext(mySize);

        UIImage *backgroundImage = [UIImage imageNamed:anImage];
        CGRect elementSymbolRectangle = CGRectMake(0.0f ,0.0f, aFrame.size.width, aFrame.size.height);
        [backgroundImage drawInRect:elementSymbolRectangle];

        // draw the element name
        [[UIColor whiteColor] set];

        // draw the element number
        UIFont *font = [UIFont boldSystemFontOfSize:(smallFontSize)];
        CGPoint point = CGPointMake(2,1);
        [self.atomicNumber drawAtPoint:point withFont:font];

        // draw the element symbol

        font = [UIFont boldSystemFontOfSize:largeFontSize];
        CGSize stringSize = [self.symbol sizeWithFont:font];
        point = CGPointMake((elementSymbolRectangle.size.width-stringSize.width)/2,aFrame.size.height-(largeFontSize)-(largeFontSize/10));
        [self.symbol drawAtPoint:point withFont:font];

        //get image


        UIImage *theImage=UIGraphicsGetImageFromCurrentImageContext();

            UIGraphicsEndImageContext();

            return (theImage);
    }
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