use a CALayer as a UIImageView

Question

I would like to create a CALayer bezier path in a circle shape. And I would like to set it like it was a UIImageView (to be able to move it with animation etc.) Is it possible? If so how can I do it? Thank you.

Answer 1

I'm not sure what you mean by a "CALayer bezier path" but you have a couple of options here:

1. Create a subclass of UIView, where you draw your circle using UIBezierPath methods in the drawRect:. This view can then be added to another view as a subview and animated using standard methods. However, you are warned that this may affect performance, (as it has to keep re-drawing) so if that does turn out to be a problem...
2. Create a graphics context and draw your circle in there. Take an image from this graphics context and set it as the image for a UIImageView. Animate as in answer (1). This way you aren't redrawing all the time so performance would be better, but try with option 1 first as it is simpler, and if you have simple drawing code it shouldn't affect you too much.

For option 2, you begin a graphics context using UIGraphicsBeginImageContextWithOptions - you then do your drawing, and extract the image using UIGraphicsGetImageFromCurrentImageContext, then end the context using UIGraphicsEndImageContext. Those functions are all documented here

Sample code to do this:

CGFloat radius = 50;
CGSize size = CGSizeMake(radius*2,radius*2);
CGPoint centre = CGPointMake(radius,radius);

UIGraphicsBeginImageContextWithOptions(size,NO, 0.0);
UIBezierPath * solidPath = [UIBezierPath bezierPathWithArcCenter:centre radius:edgeSize/20 startAngle:0 endAngle:2 * M_PI clockwise:YES];
[solidPath closePath];
[[UIColor whiteColor] set];
[solidPath fill];

UIImage *circle = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageView *imageView = [[UIImageView alloc] initWithImage:circle];