view的陰影屬性主要有5個(gè)
//shadowColor      //陰影顏色
//shadowOpacity    //陰影不透明度
//shadowRadius     //陰影半徑
//shadowOffset     //陰影偏移量 
//shadowPath       //陰影路徑
//前四個(gè)屬性的效果
UIView * view = [[UIView alloc] initWithFrame:CGRectMake(30, 100, self.view.bounds.size.width-60, 200)];
view.backgroundColor = [UIColor whiteColor];
view.layer.shadowColor = [UIColor redColor].CGColor;
view.layer.shadowOpacity = 1;   //陰影不透明度 【0-1】 0->完全透明   1->完全不透明  越大越明顯  默認(rèn)0
view.layer.shadowRadius = 20;       //陰影半徑  默認(rèn)3
view.layer.shadowOffset = CGSizeMake(0, 0); //陰影偏移量 （右，下） 默認(rèn)（0，-3）
[self.view addSubview:view];

效果圖

添加以下代碼設(shè)置貝塞爾曲線

//view.layer.shadowPath  貝塞爾曲線
UIBezierPath *path = [UIBezierPath bezierPath];

float width = view.bounds.size.width;
float height = view.bounds.size.height;
float x = view.bounds.origin.x;
float y = view.bounds.origin.y;
float addWH = 40;

CGPoint topLeft      = view.bounds.origin;  //左上角
CGPoint topMiddle = CGPointMake(x+(width/2),y-addWH);  //中上點(diǎn)
CGPoint topRight     = CGPointMake(x+width,y);  //右上角
CGPoint rightMiddle = CGPointMake(x+width+addWH,y+(height/2)); //右中點(diǎn)
CGPoint bottomRight  = CGPointMake(x+width,y+height);  //右下角
CGPoint bottomMiddle = CGPointMake(x+(width/2),y+height+addWH); //中下點(diǎn)
CGPoint bottomLeft   = CGPointMake(x,y+height);  //左下角
CGPoint leftMiddle = CGPointMake(x-addWH,y+(height/2));  //左中點(diǎn)

[path moveToPoint:topLeft];
//添加四個(gè)二元曲線
//左上角到右上角，中上為控制點(diǎn)
[path addQuadCurveToPoint:topRight
             controlPoint:topMiddle];
//右上角到右下角，右中為控制點(diǎn)
[path addQuadCurveToPoint:bottomRight
             controlPoint:rightMiddle];
//右下角到左下角，中下為控制點(diǎn)
[path addQuadCurveToPoint:bottomLeft
             controlPoint:bottomMiddle];
//左下角到左上角，左中為控制點(diǎn)
[path addQuadCurveToPoint:topLeft
             controlPoint:leftMiddle];
//設(shè)置陰影路徑
view.layer.shadowPath = path.CGPath;

[self.view addSubview:view];

效果圖