How to make a circular UIView

Question

I want to make a UIView or UIImageView that is a circle. Or a circle that i can change the size of using a slider, and the color of with a pickerview.

Answer 1

I think you would have to draw your own circle using the Core Graphics Framework

Answer 2

You need to make a transparent UIView (background color alpha of 0), and then, in its drawRect:, draw your circle using CoreGraphics calls. You could also edit the view's layer, and give it a cornerRadius.

Answer 3

Check Stanford University iPhone programming course. Lecture 4/5, for the "Hello Poly" sample application. There you change the number of polygon corners with buttons, but that could as well be a slider for circle size.

http://www.stanford.edu/class/cs193p/cgi-bin/index.php

Answer 4

I can at least show you a shortcut for drawing circles of arbitrary size. No OpenGL, no Core Graphics drawing needed.

Import the QuartzCore framework to get access to the .cornerRadius property of your UIView or UIImageView.

#import <QuartzCore/QuartzCore.h>

Also manually add it to your project's Frameworks folder.

Add this method to your view controller or wherever you need it:

-(void)setRoundedView:(UIImageView *)roundedView toDiameter:(float)newSize;
{
    CGPoint saveCenter = roundedView.center;
    CGRect newFrame = CGRectMake(roundedView.frame.origin.x, roundedView.frame.origin.y, newSize, newSize);
    roundedView.frame = newFrame;
    roundedView.layer.cornerRadius = newSize / 2.0;
    roundedView.center = saveCenter;
}

To use it, just pass it a UIImageView and a diameter. This example assumes you have a UIImageView named "circ" added as a subview to your view. It should have a backgroundColor set so you can see it.

[self setRoundedView:circ toDiameter:100.0];

This just handles UIImageViews but you can generalize it to any UIView.