iphone - Unicode Character Not Showing

Question

I want to display the "infinity" symbol using

CGContextSelectFont(context, "HelveticaNeue", textSize, kCGEncodingMacRoman);    
CGContextShowTextAtPoint(context, myCenter.x, myCenter.y + textHeight, [sName     cStringUsingEncoding:NSMacOSRomanStringEncoding], [sName length]); 

It is displayed as a square box, or a circle. I have found out this symbol is in decimal 176 and 221E in Hexadecimal format. I am using Helvetica as my font, and have tried others with no luck. Is this a problem with the encoding I am using?

Answer 1

It turns out that CGContextSelectFont only supports MacRoman encoding, which is basically has only a small set of characters. In order to display Unicode characters in a string, you have to use CGSetFont or the Cocoa drawing system. CGSetFont requires that you use Cocoa anyway to map characters to glyphs and then draw the glyphs using CGContextShowGlyphsAtPoint. I recommend that you look into other ways to draw these strings if you really need to display Unicode characters.

This code basically will display the infinity symbol:

- (void)drawRect:(CGRect)rect {
    unichar inf = 0x221E; // infinity symbol
    NSString* sName = [[NSString alloc] initWithCharacters:&inf length:1];
    UIFont* font = [UIFont fontWithName:@"Helvetica" size:32.0];
    [sName drawInRect:CGRectMake(20, 20, 40, 40)
             withFont:font];
    [sName release];
}

Also note that on the iPhone (and on the Mac) Helvetica Neue actually does not exist... its name just maps back to standard Helvetica. See the table at http://daringfireball.net/misc/2007/07/iphone-osx-fonts for more information on available fonts on the iPhone.