設定文字和圖片的方法：

1. 繪製文字的步驟是：設定NSAttributedString 或NSMutableAttributedString——> 通過attributedString 生成frameSetter ——> 生成CTFrame——>畫出來
2. 設定文字屬性，重點是在NSMutableAttributedString的生成，對顏色、字型、字距進行設定。
   
3. CoreText 中並沒有畫圖片的方法，我們同樣的在NSMutableAttributedString中插入一個空字元，然後設定這個空字元佔的位置和大小。把整個字串寫完以後。重點在這裡：解析生成的NSAttributedString，獲取到圖片應該畫的位置和大小，利用Core Graphics 把圖片畫到context中。

註釋全部寫在例子對應的位置上：

- (void)drawRect:(CGRect)rect
{
    CGContextRef contxt = UIGraphicsGetCurrentContext();
    CGContextSetTextMatrix(contxt, CGAffineTransformIdentity);
   
    CGAffineTransform flipVertical = CGAffineTransformMake(1, 0, 0, -1, 0, self.bounds.size.height);
    CGContextConcatCTM(contxt, flipVertical);
   
   
    NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc]initWithString:@"1.設定字形變換矩陣為CGAffineTransformIdentity，也就是說每一個字形都不做圖形變換，將當前context的座標系進行flip，2.為圖片設定CTRunDelegate,delegate決定留給圖片的空間大小。 3.把圖片畫上去" ];
    [attributedString addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:20] range:NSMakeRange(0, [attributedString length])];
    [attributedString addAttribute:NSForegroundColorAttributeName value:[UIColor blueColor] range:NSMakeRange(0.0, 10)];
    [attributedString addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:NSMakeRange(10, 20)];
   
    //建立圖片位置
    NSString *taobaoImageName = @"meile.png";
    CTRunDelegateCallbacks imageCallbacks;
    imageCallbacks.version = kCTRunDelegateVersion1;
    imageCallbacks.dealloc = RunDelegateDeallocCallback;
    imageCallbacks.getAscent = RunDelegateGetAscentCallback;
    imageCallbacks.getDescent = RunDelegateGetDescentCallback;
    imageCallbacks.getWidth = RunDelegateGetWidthCallback;
   
    CTRunDelegateRef runDelegate = CTRunDelegateCreate(&imageCallbacks, (__bridge void *)taobaoImageName);
    NSMutableAttributedString *imageAttributedString =[[NSMutableAttributedString alloc]initWithString:@" "];//建立一個空格，來使attributedString生效
    [imageAttributedString addAttribute:(NSString *)kCTRunDelegateAttributeName value:(__bridge id)runDelegate range:NSMakeRange(0, 1)];//設定回撥
    CFRelease(runDelegate);
   
    [imageAttributedString addAttribute:@"imageName" value:taobaoImageName range:NSMakeRange(0, 1)];
    [attributedString insertAttributedString:imageAttributedString atIndex:30];//把attribute 插入到一個特定的位置
    //建立圖片位置至此完成那個
   
   
    CTFramesetterRef ctFrameSetter = CTFramesetterCreateWithAttributedString((CFMutableAttributedStringRef)attributedString);
    CGMutablePathRef path = CGPathCreateMutable();
    CGRect bounds = CGRectMake(0.0, 20.0, self.bounds.size.width, self.bounds.size.height-20);
    CGPathAddRect(path, NULL, bounds);
   
    CTFrameRef ctFrame = CTFramesetterCreateFrame(ctFrameSetter, CFRangeMake(0, 0), path, NULL);
    CTFrameDraw(ctFrame, contxt);
   
    //現在開始畫圖片
    CFArrayRef lines = CTFrameGetLines(ctFrame);
    CGPoint lineOrigins [CFArrayGetCount(lines)]; //這是一個方法
    CTFrameGetLineOrigins(ctFrame, CFRangeMake(0, 0), lineOrigins);

   
    for (int i = 0; i < CFArrayGetCount(lines); i++) {
        CTLineRef line = CFArrayGetValueAtIndex(lines, i);
        CGFloat lineAscent;
        CGFloat lineDescent;
        CGFloat lineLeading;
        CTLineGetTypographicBounds(line, &lineAscent, &lineDescent, &lineLeading);
       
        CFArrayRef runs = CTLineGetGlyphRuns(line);
        for (int j = 0; j < CFArrayGetCount(runs); j++) {
            CGFloat runAscent;
            CGFloat runDescent;
            CGPoint lineOrigin = lineOrigins[i];
            CTRunRef run = CFArrayGetValueAtIndex(runs, j);
            NSDictionary* attributes = (NSDictionary*)CTRunGetAttributes(run);
            CGRect runRect;
            runRect.size.width = CTRunGetTypographicBounds(run, CFRangeMake(0,0), &runAscent, &runDescent, NULL);
           
            runRect=CGRectMake(lineOrigin.x + CTLineGetOffsetForStringIndex(line, CTRunGetStringRange(run).location, NULL), lineOrigin.y - runDescent, runRect.size.width, runAscent + runDescent);
           
            NSString *imageName = [attributes objectForKey:@"imageName"];
            //圖片渲染邏輯
            if (imageName)
            {
                UIImage *image = [UIImage imageNamed:imageName];
                if (image)
                {
                    CGRect imageDrawRect;
                    imageDrawRect.size = image.size;
                    imageDrawRect.origin.x = runRect.origin.x + lineOrigin.x;
                    imageDrawRect.origin.y = lineOrigin.y +lineDescent+10;// 怎麼精確計算
                    CGContextDrawImage(contxt, imageDrawRect, image.CGImage);
                }
            }
        }
    }
   
   
   
    //畫圖片結束
   
    CFRelease(ctFrame);
    CFRelease(path);
    CFRelease(ctFrameSetter);
}
 

下的DemoCoreText