iPhone - Draw white text on black view using CGContext

Question

I can't achieve drawing some white text on a black view using CGContext in a drawRect method.

I do :

CGContextRef context = UIGraphicsGetCurrentContext();

CGContextSetStrokeColorWithColor(context, [UIColor whiteColor].CGColor);
CGContextSetFillColorWithColor(context, [UIColor whiteColor].CGColor);
CGContextSetLineWidth(context, 1.0);
CGContextSelectFont(context, "Helvetica", 20, kCGEncodingMacRoman);
CGContextSetTextDrawingMode(context, kCGTextFill);

CGPoint center = self.center;

And then...
Impossible to find the correct method.
I've tried this :

UIFont* font = [UIFont fontWithName:@"Geneva" size:12.0];
[@"Some text" drawAtPoint:center withFont:font];

But it does not work.

I don't find any CGContext method for that. Where is it hidden ?

How may I draw that text in white ?

Solution 1

Works with :

CGContextShowTextAtPoint (context, center.x, center.y, "Some text", strlen("Some text")); 

But still need some transformations to be displayed not mirrored :-)

Solution 2

Ok after a couple of hours and reading the Quartz 2D programming guide I discovered that you also have to set the FILL color, not just the STROKE color. So the follow code works.

CGContextSetStrokeColorWithColor(context, [UIColor whiteColor].CGColor);
CGContextSetFillColorWithColor(context, [UIColor whiteColor].CGColor);

I needed to show chart labels on a darkGray border. Now the labels appear in white.

Solution 3

This will draw a string in white in a black rectangle

NSString *text = @"Some text";
CGPoint center = CGPointMake(100, 200);
UIFont *font = [UIFont systemFontOfSize:14];

CGSize stringSize = [text sizeWithFont:font];
CGRect stringRect = CGRectMake(center.x-stringSize.width/2, center.y-stringSize.height/2, stringSize.width, stringSize.height);

[[UIColor blackColor] set];
CGContextFillRect(context, stringRect);

[[UIColor whiteColor] set];
[text drawInRect:stringRect withFont:font];

Solution 4

On shorter example try using [[UIColor whiteColor] set] before the drawAtPoint: call.

View more solutions

Comments

[Marcelo Alves]

are you sure your drawRect: is being called? Just tried here with a small sample and it works flawlessly.

[amattn]

Be careful. Last I checked, this only works for ASCII, not Unicode.

[Oliver]

OK, but that didn't work. The method I give in my found solution solved the preblem (but text is mirrored).

[fishinear]

Actually, you only need to set the fill color, the stroke color is not used by text

[Todd Lehman]

Note that you can also write UIColor.whiteColor.CGColor in Objective-C 2.0 dot syntax.

[Ky -]

'CGContextShowTextAtPoint' is unavailable: APIs deprecated as of OS X 10.9 and earlier are unavailable in Swift