在 imageview 目标 c 上绘制圆圈

Question

我正在尝试在 ios 应用程序的图像视图上绘制圆圈，会有很多圆圈，我希望它们位于同一层。我的画圆代码是；

UIBezierPath *circle = [UIBezierPath bezierPathWithArcCenter:center
                                                      radius:radius
                                                  startAngle:0
                                                    endAngle:2.0*M_PI
                                                   clockwise:YES];

CAShapeLayer *circleLayer = [CAShapeLayer layer];
circleLayer.bounds = CGRectMake(0, 0, 2.0*radius, 2.0*radius);
circleLayer.path   = circle.CGPath;
circleLayer.backgroundColor = [UIColor orangeColor].CGColor;

我需要一些不同于下面代码的东西；

[imageView.layer addSublayer:circleLayer];

谢谢。

Answer 1

来自这个网站：http://www.cocoanetics.com/2010/07/drawing-on-uiimages/

- (UIImage *)imageByDrawingCircleOnImage:(UIImage *)image
{
    // begin a graphics context of sufficient size
    UIGraphicsBeginImageContext(image.size);

    // draw original image into the context
    [image drawAtPoint:CGPointZero];

    // get the context for CoreGraphics
    CGContextRef ctx = UIGraphicsGetCurrentContext();

    // set stroking color and draw circle
    [[UIColor redColor] setStroke];

    // make circle rect 5 px from border
    CGRect circleRect = CGRectMake(0, 0,
                image.size.width,
                image.size.height);
    circleRect = CGRectInset(circleRect, 5, 5);

    // draw circle
    CGContextStrokeEllipseInRect(ctx, circleRect);

    // make image out of bitmap context
    UIImage *retImage = UIGraphicsGetImageFromCurrentImageContext();

    // free the context
    UIGraphicsEndImageContext();

    return retImage;
}