为控件设置圆角加阴影(万能法则)

//切圆角加阴影
- (void)addShadowToView:(UIView *)view
            withOpacity:(float)shadowOpacity
          withShowColor:(UIColor*)shadowColor
           shadowRadius:(CGFloat)shadowRadius
        andCornerRadius:(CGFloat)cornerRadius
{
    //////// shadow /////////
    _shadowLayer = [CALayer layer];
    _shadowLayer.frame = view.layer.frame;
    
    _shadowLayer.shadowColor = shadowColor.CGColor;//shadowColor阴影颜色
    _shadowLayer.shadowOffset = CGSizeMake(0, 5);//shadowOffset阴影偏移，默认(0, -3),这个跟shadowRadius配合使用
    _shadowLayer.shadowOpacity = shadowOpacity;//0.8;//阴影透明度，默认0
    _shadowLayer.shadowRadius = shadowRadius;//8;//阴影半径，默认3
    
    //路径阴影
    UIBezierPath *path = [UIBezierPath bezierPath];
    
    float width = _shadowLayer.bounds.size.width;
    float height = _shadowLayer.bounds.size.height;
    float x = _shadowLayer.bounds.origin.x;
    float y = _shadowLayer.bounds.origin.y;
    
    CGPoint topLeft      = _shadowLayer.bounds.origin;
    CGPoint topRight     = CGPointMake(x + width, y);
    CGPoint bottomRight  = CGPointMake(x + width, y + height);
    CGPoint bottomLeft   = CGPointMake(x, y + height);
    
    CGFloat offset = -1.f;
    [path moveToPoint:CGPointMake(topLeft.x - offset, topLeft.y + cornerRadius)];
    [path addArcWithCenter:CGPointMake(topLeft.x + cornerRadius, topLeft.y + cornerRadius) radius:(cornerRadius + offset) startAngle:M_PI endAngle:M_PI_2 * 3 clockwise:YES];
    [path addLineToPoint:CGPointMake(topRight.x - cornerRadius, topRight.y - offset)];
    [path addArcWithCenter:CGPointMake(topRight.x - cornerRadius, topRight.y + cornerRadius) radius:(cornerRadius + offset) startAngle:M_PI_2 * 3 endAngle:M_PI * 2 clockwise:YES];
    [path addLineToPoint:CGPointMake(bottomRight.x + offset, bottomRight.y - cornerRadius)];
    [path addArcWithCenter:CGPointMake(bottomRight.x - cornerRadius, bottomRight.y - cornerRadius) radius:(cornerRadius + offset) startAngle:0 endAngle:M_PI_2 clockwise:YES];
    [path addLineToPoint:CGPointMake(bottomLeft.x + cornerRadius, bottomLeft.y + offset)];
    [path addArcWithCenter:CGPointMake(bottomLeft.x + cornerRadius, bottomLeft.y - cornerRadius) radius:(cornerRadius + offset) startAngle:M_PI_2 endAngle:M_PI clockwise:YES];
    [path addLineToPoint:CGPointMake(topLeft.x - offset, topLeft.y + cornerRadius)];
    
    //设置阴影路径
    _shadowLayer.shadowPath = path.CGPath;
    
    //////// cornerRadius /////////
    view.layer.cornerRadius = cornerRadius;
    view.layer.masksToBounds = YES;
    view.layer.shouldRasterize = YES;
    view.layer.rasterizationScale = [UIScreen mainScreen].scale;
    
    //[view.superview.layer removeFromSuperlayer];
    [view.superview.layer insertSublayer:_shadowLayer below:view.layer];
    
}