C String in iOS looks blurry - ios

Question

I have been trying to render text in a arc . the text rendered as expected but it looks blurry. how can i fix this issue.
- (UIImage*) createMenuRingWithFrame:(CGRect)frame
{
NSArray* sections = [[NSArray alloc] initWithObjects:#"daily", #"yearly", #"monthly", #"weekly",nil];
CGRect imageSize = frame;
float perSectionDegrees = 360 / [sections count];
float totalRotation = 135;
float fontSize = ((frame.size.width/2) /2)/2;
self.menuItemsFont = [UIFont fontWithName:#"Avenir" size:fontSize];
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, imageSize.size.width, imageSize.size.height, 8, 4 * imageSize.size.width, colorSpace,(CGBitmapInfo) kCGImageAlphaPremultipliedFirst);
CGPoint centerPoint = CGPointMake(imageSize.size.width / 2, imageSize.size.height / 2);
double radius = (frame.size.width / 2)-2;
for (int index = 0; index < [sections count]; index++)
{
BOOL textRotationDown = NO;
NSString* menuItemText = [sections objectAtIndex:index];
CGSize textSize = [menuItemText sizeWithAttributes:
#{NSFontAttributeName: self.menuItemsFont}];
char* menuItemTextChar = (char*)[menuItemText cStringUsingEncoding:NSASCIIStringEncoding];
if (totalRotation>200.0 && totalRotation <= 320.0) {
textRotationDown = YES;
}
else
textRotationDown= NO;
float x = centerPoint.x + radius * cos(DEGREES_TO_RADIANS(totalRotation));
float y = centerPoint.y + radius * sin(DEGREES_TO_RADIANS(totalRotation));
CGContextSaveGState(context);
CFStringRef font_name = CFStringCreateWithCString(NULL, "Avenir", kCFStringEncodingMacRoman);
CTFontRef font = CTFontCreateWithName(font_name, fontSize, NULL);
CFStringRef keys[] = { kCTFontAttributeName };
CFTypeRef values[] = { font };
CFDictionaryRef font_attributes = CFDictionaryCreate(kCFAllocatorDefault, (const void **)&keys, (const void **)&values, sizeof(keys) / sizeof(keys[0]), &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
CFRelease(font_name);
CFRelease(font);
CFStringRef string = CFStringCreateWithCString(NULL, menuItemTextChar, kCFStringEncodingMacRoman);
CFAttributedStringRef attr_string = CFAttributedStringCreate(NULL, string, font_attributes);
CTLineRef line = CTLineCreateWithAttributedString(attr_string);
CGContextTranslateCTM(context, x, y);
CGContextRotateCTM(context, DEGREES_TO_RADIANS(totalRotation - (textRotationDown?275:90)));
CGContextSetTextPosition(context,0 - (textSize.width / 2), 0 - (textSize.height / (textRotationDown?20:4)));
CTLineDraw(line, context);
CFRelease(line);
CFRelease(string);
CFRelease(attr_string);
CGContextRestoreGState(context);
totalRotation += perSectionDegrees;
}
CGImageRef contextImage = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
return [UIImage imageWithCGImage:contextImage];
}

Answer 1

One problem is that you are not allowing for screen resolution. Make your bitmap context twice as big, or three times as big; multiply all the values appropriately (this is easiest if you just apply a scale CTM at the outset); and then at the end, instead of calling imageWithCGImage:, call imageWithCGImage:scale:orientation:, setting the corresponding scale.
If you had created your context with UIGraphicsBeginImageContextWithOptions, that would have happened automatically (if you had provided a third argument of zero), or you could explicitly have set the third argument to provide a scale for the context and hence the image derived from it. But by building your context manually, you threw away the capacity to provide it with a scale.