Layout text on the image with Core Text - ios

Question

guys.
I have do rich text eidtor some work with Core Text.I want to keep fixed line height and it truely can be done with the following code:
NSMutableAttributedString *_attributedText = [[NSMutableAttributedString alloc]initWithAttributedString:_attributedString] ;
CGFloat lineSpace=20;
CTParagraphStyleSetting lineSpaceStyle;
lineSpaceStyle.spec=kCTParagraphStyleSpecifierMaximumLineHeight;
lineSpaceStyle.valueSize=sizeof(lineSpace);
lineSpaceStyle.value=&lineSpace;
//CTLineBreakMode lineBreakMode = kCTLineBreakByCharWrapping;
CTParagraphStyleSetting settings[]={
lineSpaceStyle,
// {.spec = kCTParagraphStyleSpecifierLineBreakMode, .valueSize = sizeof(CTLineBreakMode), .value = (const void*)&lineBreakMode},
};
CTParagraphStyleRef paragraphStyle = CTParagraphStyleCreate(settings, sizeof(settings));
[_attributedText addAttribute:(id)kCTParagraphStyleAttributeName value:(id)paragraphStyle range:NSMakeRange(0, _attributedText.mutableString.length)];
_attributedString = [_attributedText copy];
[_attributedText release];
_attributedText = nil;
CFRelease(paragraphStyle);
Then I want to insert an image into it.And I want type some text on the image with following code:
CTRunDelegateCallbacks callbacks = {
.version = kCTRunDelegateVersion1,
.dealloc = AttachmentRunDelegateDealloc,
.getAscent = AttachmentRunDelegateGetAscent,
.getDescent = AttachmentRunDelegateGetDescent,
.getWidth = AttachmentRunDelegateGetWidth
};
CTRunDelegateRef Rundelegate = CTRunDelegateCreate(&callbacks, [image retain]); //3
NSMutableDictionary *attrDictionaryDelegate = [NSMutableDictionary dictionaryWithDictionary:self.defaultAttributes];
[attrDictionaryDelegate setObject:image
forKey:EGOTextAttachmentAttributeName];
[attrDictionaryDelegate setObject:(id)Rundelegate
forKey:(NSString*)kCTRunDelegateAttributeName];
[attrDictionaryDelegate setObject:fulltext
forKey:EGOTextAttachmentOriginStringKey];
NSAttributedString *newString = [[NSAttributedString alloc] initWithString:EGOTextAttachmentPlaceholderString
attributes:attrDictionaryDelegate];
[attrString replaceCharactersInRange:[result resultByAdjustingRangesWithOffset:attrString.length-astring.length].range
withAttributedString:newString];
In another words,is there some ways to let the text layout on the image with Core Text ?????
Anyone????

Answer 1

Very Easy
keep fixed line height with CoreText,
let the text layout on the image by image.draw(in: frame) ,
maybe frame calculated with CoreText .
here is an example, put a background image below the first word in the line
// here is set up
guard let ctx = UIGraphicsGetCurrentContext(), let f = frameRef else{
return
}
let xHigh = bounds.size.height
ctx.textMatrix = CGAffineTransform.identity
ctx.translateBy(x: 0, y: xHigh)
ctx.scaleBy(x: 1.0, y: -1.0)
guard let lines = CTFrameGetLines(f) as? [CTLine] else{
return
}
// here is an image
let bgGrip = UIImage(named: "grip")
if let pieces = CTLineGetGlyphRuns(line) as? [CTRun]{
let pieceCnt = pieces.count
for i in 0..<pieceCnt{
var p = lineOrigin
if i == 0{
var frame = imageFrame
frame.origin.y = lineOrigin.y + lineAscent - imageHeight + TextContentConst.offsetP.y
bgGrip?.draw(in: frame)
p.x += offsetX
}
ctx.textPosition = p
CTRunDraw(pieces[i], ctx, CFRange(location: 0, length: 0))
}
}