I would like to draw the content of a NSString
variable in a UIImage
, but I have absolutely no idea how to do this. I need to write a method that w
Begin an image context with UIGraphicsBeginImageContext
, draw to it, get an image with UIGraphicsGetImageFromCurrentImageContext
, end it with UIGraphicsEndImageContext
Adding a Swift version, also gives you more options:
class func sizeOfAttributeString(str: NSAttributedString, maxWidth: CGFloat) -> CGSize {
let size = str.boundingRectWithSize(CGSizeMake(maxWidth, 1000), options:(NSStringDrawingOptions.UsesLineFragmentOrigin), context:nil).size
return size
}
class func imageFromText(text:NSString, font:UIFont, maxWidth:CGFloat, color:UIColor) -> UIImage {
let paragraph = NSMutableParagraphStyle()
paragraph.lineBreakMode = NSLineBreakMode.ByWordWrapping
paragraph.alignment = .Center // potentially this can be an input param too, but i guess in most use cases we want center align
let attributedString = NSAttributedString(string: text, attributes: [NSFontAttributeName: font, NSForegroundColorAttributeName: color, NSParagraphStyleAttributeName:paragraph])
let size = sizeOfAttributeString(attributedString, maxWidth: maxWidth)
UIGraphicsBeginImageContextWithOptions(size, false , 0.0)
attributedString.drawInRect(CGRectMake(0, 0, size.width, size.height))
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image
}
Swift 3.1
func sizeOfAttributeString(str: NSAttributedString, maxWidth: CGFloat) -> CGSize {
let size = str.boundingRect(with: CGSize(width: maxWidth, height: 1000), options:(NSStringDrawingOptions.usesLineFragmentOrigin), context:nil).size
return size
}
func imageFromText(text:NSString, font:UIFont, maxWidth:CGFloat, color:UIColor) -> UIImage {
let paragraph = NSMutableParagraphStyle()
paragraph.lineBreakMode = NSLineBreakMode.byWordWrapping
paragraph.alignment = .center
let attributedString = NSAttributedString(string: text as String, attributes: [NSFontAttributeName: font, NSForegroundColorAttributeName: color, NSParagraphStyleAttributeName:paragraph])
let size = sizeOfAttributeString(str: attributedString, maxWidth: maxWidth)
UIGraphicsBeginImageContextWithOptions(size, false , 0.0)
attributedString.draw(in: CGRect(x: 0, y: 0, width: size.width, height: size.height))
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image!
}
Credit goes to Bao Lei for the beautiful answer.
You can try this: (updated for iOS 4)
-(UIImage *)imageFromText:(NSString *)text
{
// set the font type and size
UIFont *font = [UIFont systemFontOfSize:20.0];
CGSize size = [text sizeWithFont:font];
// check if UIGraphicsBeginImageContextWithOptions is available (iOS is 4.0+)
if (UIGraphicsBeginImageContextWithOptions != NULL)
UIGraphicsBeginImageContextWithOptions(size,NO,0.0);
else
// iOS is < 4.0
UIGraphicsBeginImageContext(size);
// optional: add a shadow, to avoid clipping the shadow you should make the context size bigger
//
// CGContextRef ctx = UIGraphicsGetCurrentContext();
// CGContextSetShadowWithColor(ctx, CGSizeMake(1.0, 1.0), 5.0, [[UIColor grayColor] CGColor]);
// draw in context, you can use also drawInRect:withFont:
[text drawAtPoint:CGPointMake(0.0, 0.0) withFont:font];
// transfer image
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
To call it:
UIImage *image = [self imageFromText:@"This is a text"];