Tested Code:
.h
#import <QuartzCore/QuartzCore.h>
-(void)roundButtonDidTap:(UIButton*)tappedButton;
.m
#define ROUND_BUTTON_WIDTH_HEIGHT YourButtonWidthToBeSetHere
-(void)roundButtonDidTap:(UIButton*)tappedButton{
NSLog(@"roundButtonDidTap Method Called");
}
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
[button setImage:[UIImage imageNamed:@"TimoonPumba.png"] forState:UIControlStateNormal];
[button addTarget:self action:@selector(roundButtonDidTap:) forControlEvents:UIControlEventTouchUpInside];
//width and height should be same value
button.frame = CGRectMake(0, 0, ROUND_BUTTON_WIDTH_HEIGHT, ROUND_BUTTON_WIDTH_HEIGHT);
//Clip/Clear the other pieces whichever outside the rounded corner
button.clipsToBounds = YES;
//half of the width
button.layer.cornerRadius = ROUND_BUTTON_WIDTH_HEIGHT/2.0f;
button.layer.borderColor=[UIColor redColor].CGColor;
button.layer.borderWidth=2.0f;
[self.view addSubview:button];
Result
Geometry in this concept