I want to know whether drawing a round UIButton(not rounded rect) is possible.
When I add a round image in a UIButton of type custom, then it looks like a round button. But at the moment the button is clicked the boundary of the button becomes visible, so that it looks like a square button, then again when the click ends it looks like a round button.
I want the button to look like a round button even at the moment the click happens. is this possible?
You'd probably have to create a custom control for that, but do you really need a round button?
Every platform has its UI conventions, and the iPhone is no exception. Users expect the buttons to be rounded rectangles.
UPDATE in response to comment:
If I'm getting this right, you're not looking for a round button, but rather a clickable (touchable) image.
You can use an UIImageView and its touchesBegan method.
UPDATE 2:
Wait a second. What kind of radio button are we talking about? For some reason I thought you were trying to imitate a real radio. If you're talking about a radio button group, please use a UISegmentedControl or a UIPicker.