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Editorial Team
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Asked: 2026-06-18T12:09:32+00:00

I’m just trying to overlay a text in a UIImage (using CGContext) but it

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I’m just trying to overlay a text in a UIImage (using CGContext) but it doesn’t show the text I specified. In this code I’m giving as the text argument "Hello" but it shows “eÉääc”. I don’t know what’s happening I think the characters are displaced but I don’t know how to solve it.
This is my code:

UIGraphicsBeginImageContextWithOptions(image.size, YES, 0);
CGContextRef c = UIGraphicsGetCurrentContext();
[image drawInRect:CGRectMake(0, 0, image.size.width, image.size.height)];
CGContextSetTextMatrix(c, CGAffineTransformMake(1.0, 0, 0, -1.0, 0, 0));
CGContextSelectFont(c, "ArialMT", 50, kCGEncodingFontSpecific);
CGContextSetRGBStrokeColor(c, 255, 0, 0, 1);
CGContextSetRGBFillColor(c, 255, 0, 0, 1);
CGContextSetCharacterSpacing(c, 2);
CGContextShowTextAtPoint(c,100,100, "Hello", 5);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

I’m using the Spanish Keyboard (I don’t know if this matters) and the iPad (where I’m testing the application) is in Catalan.

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1 Answer

  1. Editorial Team

    CGContextShowTextAtPoint() interprets the given text according to the specified encoding parameter of CGContextSelectFont. You have chosen kCGEncodingFontSpecific, which is the font built-in encoding (whatever that might be).

    The only other choice is kCGEncodingMacRoman:

    CGContextSelectFont(c, "ArialMT", 50, kCGEncodingMacRoman);

    Then your text should display correctly, as long as you use only characters from the ASCII character set.

    For non-ASCII characters, you have to convert the string to the MacRoman encoding, see e.g. https://stackoverflow.com/a/13743834/1187415 for an example.

    Note that CGContextShowTextAtPoint cannot display general Unicode strings, and even has problems with the Euro (€) character. The drawAtPoint:withFont: method of NSString does not have these limitations.

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