iPhone - Using CGContextShowTextAtPoint to draw special characters

问题

I am creating sub class for UILabel to adjust the character spacing. It works well. But when I use special characters as in Spanish or Japanese language, its not writing. Only english characters are written properly. Any solution on how to display them?

- (void) drawRect:(CGRect)rect 
{

    // Drawing code
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSelectFont (context, [self.font.fontName cStringUsingEncoding:NSUTF8StringEncoding], self.font.pointSize, kCGEncodingMacRoman);
    CGContextSetCharacterSpacing(context, -1);
    CGContextSetFillColorWithColor(context, [[UIColor clearColor] CGColor]);
    CGAffineTransform myTextTransform = CGAffineTransformScale(CGAffineTransformIdentity, 1.f, -1.f );
    CGContextSetTextMatrix (context, myTextTransform);

    // draw 1 but invisbly to get the string length.
    const char* str = [self.text UTF8String];

    CGPoint p = CGContextGetTextPosition(context);
    float centeredY = (self.font.pointSize + (self.frame.size.height - self.font.pointSize)/2)-2;
    CGContextShowTextAtPoint(context, 0, centeredY, str, [self.text length]);
    CGPoint v = CGContextGetTextPosition(context);

    float centeredX = 0;
    if (self.centered) {
        float width = v.x - p.x;
        centeredX = (self.frame.size.width- width)/2;
    }
    // calculate width and draw second one.
    CGContextSetFillColorWithColor(context, [self.textColor CGColor]);
    CGContextShowTextAtPoint(context, centeredX, centeredY, str, [self.text length]);
}

回答1:

CGContextShowTextAtPoint does not directly support those languages -- the MacRoman encoding may have been a hint. CG has only basic text layout/drawing.

two alternatives would be Cocoa's text drawing, or CoreText.

回答2:

Better late than never;

Use CoreText to drawFonts instead (Special characters and Unicode) http://developer.apple.com/library/ios/#documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/dq_text/dq_text.html#//apple_ref/doc/uid/TP30001066-CH213-TPXREF101 "iOS 3.2 and later and Mac OS X both support Core Text, an advanced low-level technology for laying out text and handing fonts. Core Text is designed for high performance and ease of use and allows you to draw Unicode text directly to a graphics context. If you are writing an application that needs precise control over how text is displayed, see Core Text Programming Guide."

来源：https://stackoverflow.com/questions/7190005/iphone-using-cgcontextshowtextatpoint-to-draw-special-characters

标签

iphone

objective-c

cocoa-touch

uilabel