CoreText 设置文字属性和插入图片

设置文字和图片的方法：
绘制文字的步骤是：设置NSAttributedString 或NSMutableAttributedString——> 通过attributedString 生成frameSetter ——> 生成CTFrame——>画出来
设置文字属性，重点是在NSMutableAttributedString的生成，对颜色、字体、字距进行设置。
CoreText 中并没有画图片的方法，我们同样的在NSMutableAttributedString中插入一个空字符，然后设置这个空字符占的位置和大小。把整个字符串写完以后。重点在这里：解析生成的NSAttributedString，获取到图片应该画的位置和大小，利用Core Graphics 把图片画到context中。
注释全部写在例子对应的位置上：

#import <UIKit/UIKit.h>@interface DetailView : UIView@property (nonatomic, assign) NSInteger begin;/**< 图片开始位置 */@property (nonatomic, strong) NSString *imageblank;/**< 图片占位符 */@property (nonatomic, strong) NSString *imagename;/**< 图片名称 */@property (nonatomic, strong) NSString *detailtext;/**< 文字字符串 */@end

#import "DetailView.h"#import <CoreText/CoreText.h>@implementation DetailView// Only override drawRect: if you perform custom drawing.// An empty implementation adversely affects performance during animation.- (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:self.detailtext];    [attributedString addAttribute:NSFontAttributeName value:denzaFont(14) range:NSMakeRange(0, [attributedString length])];    [attributedString addAttribute:NSForegroundColorAttributeName value:[UIColor colorWithWhite:0.565 alpha:1.000] range:NSMakeRange(0, [attributedString length])];    //创建图片位置    NSString *taobaoImageName = self.imagename;    NSMutableAttributedString *imageAttributedString =[[NSMutableAttributedString alloc]initWithString:self.imageblank];//创建一个空格，来使attributedString生效//@" "    [imageAttributedString addAttribute:@"imageName" value:taobaoImageName range:NSMakeRange(0, 1)];    [attributedString insertAttributedString:imageAttributedString atIndex:self.begin];//把attribute 插入到一个特定的位置    //创建图片位置至此完成那个    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);    //现在开始画图片    CFArrayRef lines = CTFrameGetLines(ctFrame);    CGPoint lineOrigins [CFArrayGetCount(lines)]; //这是一个方法    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"];            //图片渲染逻辑            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;// 怎么精确计算                    CGContextDrawImage(contxt, imageDrawRect, image.CGImage);                }            }        }    }    //画图片结束    CFRelease(ctFrame);    CFRelease(path);    CFRelease(ctFrameSetter);}@end