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1，填充背景色：

    [[UIColorpurpleColor]setFill];

   UIRectFill(rect);//填充背景色：

2,设置边框颜色

    [[UIColorredColor]setFill];

   CGRect frame =CGRectMake(20,30,100, 300);

   UIRectFrame(frame);//设置边框颜色

3,给图片上面增加水印或文字

   重写UIView的- (void)drawRect:(CGRect)rect方法，然后将图形绘制到view上面，然后再增加文字或其他图层，如:

  - (void)drawRect:(CGRect)rect

   {    

    NSString* imagePath = [[NSBundlemainBundle]pathForResource:@"dog"ofType:@"png"];//rabbit

    UIImage* myImageObj = [[UIImagealloc]initWithContentsOfFile:imagePath];

    [myImageObjdrawInRect:CGRectMake(0,40,200, 300)];

    [myImageObjdrawAsPatternInRect:CGRectMake(0,0,320, 400)];

    NSString *s =@"我的小狗";

    UIFont *font = [UIFontsystemFontOfSize:34];

    NSDictionary *attr =@{

NSFontAttributeName:font};

   ［drawAtPoint:CGPointMake(100,300)withAttributes:attr];

  }

＊，绘制曲线:

- (void)drawRect:(CGRect)rect

{    

   CGContextRef cgContext =UIGraphicsGetCurrentContext();//坐标

    CGContextMoveToPoint(cgContext, 333, 0);

/*绘制曲线

    CGContextAddCurveToPoint(cgContext, 333, 0, 332, 26, 330, 26);

    CGContextAddCurveToPoint(cgContext, 330, 26, 299, 20, 299, 17);

    CGContextAddLineToPoint(cgContext, 296, 17);

    CGContextAddCurveToPoint(cgContext, 296, 17, 296, 19, 291, 19);

    CGContextAddLineToPoint(cgContext, 250, 19);

    CGContextAddCurveToPoint(cgContext, 250, 19, 241, 24, 238, 19);

    CGContextAddCurveToPoint(cgContext, 236, 20, 234, 24, 227, 24);

    CGContextAddCurveToPoint(cgContext, 220, 24, 217, 19, 216, 19);

    CGContextAddCurveToPoint(cgContext, 214, 20, 211, 22, 207, 20);

    CGContextAddCurveToPoint(cgContext, 207, 20, 187, 20, 182, 21);

    CGContextAddLineToPoint(cgContext, 100, 45);

    CGContextAddLineToPoint(cgContext, 97, 46);

    CGContextAddCurveToPoint(cgContext, 97, 46, 86, 71, 64, 72);

    CGContextAddCurveToPoint(cgContext, 42, 74, 26, 56, 23, 48);

    CGContextAddLineToPoint(cgContext, 9, 47);

    CGContextAddCurveToPoint(cgContext, 9, 47, 0, 31, 0, 0);

    CGContextStrokePath(cgContext);

}

＊，图片的缩放，平移，旋转示例

 - (void)drawRect:(CGRect)rect

 {   

    NSString *path = [[NSBundlemainBundle] pathForResource:@"cat"ofType:@"png"];

    UIImage *img = [UIImageimageWithContentsOfFile:path];

    CGImageRef image = img.CGImage;

    CGContextRef context =UIGraphicsGetCurrentContext();

    CGContextSaveGState(context);

    CGContextTranslateCTM (context,150, 200);//平移

    CGContextScaleCTM (context, 1.0, .75);//缩放

    CGContextRotateCTM (context, radians(275.));//旋转

    CGRect touchRect = CGRectMake(0, 0, img.size.width, img.size.height);

    CGContextDrawImage(context, touchRect, image);

    CGContextRestoreGState(context);

 }

还可以得用图层来平称图片:如：

    CGAffineTransform moveTransform = CGAffineTransformMakeTranslation(180, 400);

    [myImageView.layer setAffineTransform:moveTransform];//平移

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