UIBezierPath加圆角

    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];

    button.backgroundColor = [UIColor redColor];

    button.frame = CGRectMake(0, 0, 100, 44);

    CGRect bounds = button.bounds;

    UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:bounds cornerRadius:frame.size.width/2];

    CAShapeLayer *shapeLayer = [CAShapeLayer layer];

    shapeLayer.frame = bounds;

    shapeLayer.path = path.CGPath;

    button.layer.mask = shapeLayer;