UIButton 设置为圆形，并且使用图片（UIImage）当做背景

-(UIButton *)shareButtonWithIcon:(NSString *)iconName

{

UIButton *button = [UIButtonbuttonWithType:UIButtonTypeCustom];

button.frame = CGRectMake(100, 100, 2 *
50, 2 * 50);

// Circle background

UIView *circle = [[UIView alloc] initWithFrame:CGRectMake(0,
0, 2 * 50, 2 * 50)];

circle.backgroundColor = [UIColorblueColor];

circle.layer.cornerRadius = 50;

circle.layer.masksToBounds = YES;

circle.opaque = NO;

circle.alpha = 0.97;

// Circle icon

UIImageView *icon = [[UIImageView alloc] initWithImage:[UIImage imageNamed:iconName]];

CGRect f = icon.frame;

f.origin.x = (circle.frame.size.width - f.size.width) * 0.5;

f.origin.y = (circle.frame.size.height -
f.size.height) * 0.5;

icon.frame = f;

[circle addSubview:icon];

[button
setBackgroundImage:[selfimageWithView:circle] forState:UIControlStateNormal];

return button;

}

-(UIImage *)imageWithView:(UIView
*)view

{

UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.opaque, 0.0);

[view.layerrenderInContext:UIGraphicsGetCurrentContext()];

UIImage * img =
UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return img;

}