diff --git a/_posts/2013/2013-03-11-core-text.md b/_posts/2013/2013-03-11-core-text.md
index cdc89c7..ced2901 100644
--- a/_posts/2013/2013-03-11-core-text.md
+++ b/_posts/2013/2013-03-11-core-text.md
@@ -162,15 +162,16 @@ callbacks的结构体为CTRunDelegateCallbacks，主要是包含一些回调函
 {
     CGContextRef context = UIGraphicsGetCurrentContext();
     
+	//这四行代码只是简单测试drawRect中context的坐标系
     CGContextSetRGBFillColor (context, 1, 0, 0, 1);
     CGContextFillRect (context, CGRectMake (0, 200, 200, 100 ));
     CGContextSetRGBFillColor (context, 0, 0, 1, .5);
     CGContextFillRect (context, CGRectMake (0, 200, 100, 200));
+	
+    CGContextSetTextMatrix(context, CGAffineTransformIdentity);//设置字形变换矩阵为CGAffineTransformIdentity，也就是说每一个字形都不做图形变换
     
-    
-    CGContextSetTextMatrix(context, CGAffineTransformIdentity);
-    CGAffineTransform flipVertical = CGAffineTransformMake(1,0,0,-1,0,self.bounds.size.height);
-    CGContextConcatCTM(context, flipVertical);
+	CGAffineTransform flipVertical = CGAffineTransformMake(1,0,0,-1,0,self.bounds.size.height);
+    CGContextConcatCTM(context, flipVertical);//将当前context的坐标系进行flip
     
     NSMutableAttributedString *attributedString = [[[NSMutableAttributedString alloc] initWithString:@"测试富文本显示"] autorelease];