Add shadow to UIView

效果图：

 

以下代码实现：

第一个图片的代码

//加阴影--任海丽编辑
    _imageView.layer.shadowColor = [UIColor blackColor].CGColor;//shadowColor阴影颜色
    _imageView.layer.shadowOffset = CGSizeMake(4,4);//shadowOffset阴影偏移,x向右偏移4，y向下偏移4，默认(0, -3),这个跟shadowRadius配合使用
    _imageView.layer.shadowOpacity = 0.8;//阴影透明度，默认0
    _imageView.layer.shadowRadius = 4;//阴影半径，默认3

//加阴影--任海丽编辑
    _imageView.layer.shadowColor = [UIColor blackColor].CGColor;//shadowColor阴影颜色
    _imageView.layer.shadowOffset = CGSizeMake(4,4);//shadowOffset阴影偏移,x向右偏移4，y向下偏移4，默认(0, -3),这个跟shadowRadius配合使用
    _imageView.layer.shadowOpacity = 0.8;//阴影透明度，默认0
    _imageView.layer.shadowRadius = 4;//阴影半径，默认3

第二个图片的代码

 

_imageView1.layer.shadowColor = [UIColor yellowColor].CGColor;//shadowColor阴影颜色
_imageView1.layer.shadowOffset = CGSizeMake(0,0);//shadowOffset阴影偏移，默认(0, -3),这个跟shadowRadius配合使用
_imageView1.layer.shadowOpacity = 1;//阴影透明度，默认0
_imageView1.layer.shadowRadius = 3;//阴影半径，默认3

//路径阴影
UIBezierPath *path = [UIBezierPath bezierPath];

float width = _imageView1.bounds.size.width;
float height = _imageView1.bounds.size.height;
float x = _imageView1.bounds.origin.x;
float y = _imageView1.bounds.origin.y;
float addWH = 10;

CGPoint topLeft      = _imageView1.bounds.origin;
CGPoint topMiddle = CGPointMake(x+(width/2),y-addWH);
CGPoint topRight     = CGPointMake(x+width,y);

CGPoint rightMiddle = CGPointMake(x+width+addWH,y+(height/2));

CGPoint bottomRight  = CGPointMake(x+width,y+height);
CGPoint bottomMiddle = CGPointMake(x+(width/2),y+height+addWH);
CGPoint bottomLeft   = CGPointMake(x,y+height);


CGPoint leftMiddle = CGPointMake(x-addWH,y+(height/2));

[path moveToPoint:topLeft];
//添加四个二元曲线
[path addQuadCurveToPoint:topRight
             controlPoint:topMiddle];
[path addQuadCurveToPoint:bottomRight
             controlPoint:rightMiddle];
[path addQuadCurveToPoint:bottomLeft
             controlPoint:bottomMiddle];
[path addQuadCurveToPoint:topLeft
             controlPoint:leftMiddle];
//设置阴影路径
 _imageView1.layer.shadowPath = path.CGPath;

    _imageView1.layer.shadowColor = [UIColor yellowColor].CGColor;//shadowColor阴影颜色
    _imageView1.layer.shadowOffset = CGSizeMake(0,0);//shadowOffset阴影偏移，默认(0, -3),这个跟shadowRadius配合使用
    _imageView1.layer.shadowOpacity = 1;//阴影透明度，默认0
    _imageView1.layer.shadowRadius = 3;//阴影半径，默认3
    
    //路径阴影
    UIBezierPath *path = [UIBezierPath bezierPath];

    float width = _imageView1.bounds.size.width;
    float height = _imageView1.bounds.size.height;
    float x = _imageView1.bounds.origin.x;
    float y = _imageView1.bounds.origin.y;
    float addWH = 10;
    
    CGPoint topLeft      = _imageView1.bounds.origin;
    CGPoint topMiddle = CGPointMake(x+(width/2),y-addWH);
    CGPoint topRight     = CGPointMake(x+width,y);
    
    CGPoint rightMiddle = CGPointMake(x+width+addWH,y+(height/2));
    
    CGPoint bottomRight  = CGPointMake(x+width,y+height);
    CGPoint bottomMiddle = CGPointMake(x+(width/2),y+height+addWH);
    CGPoint bottomLeft   = CGPointMake(x,y+height);
    
    
    CGPoint leftMiddle = CGPointMake(x-addWH,y+(height/2));
    
    [path moveToPoint:topLeft];
    //添加四个二元曲线
    [path addQuadCurveToPoint:topRight
                 controlPoint:topMiddle];
    [path addQuadCurveToPoint:bottomRight
                 controlPoint:rightMiddle];
    [path addQuadCurveToPoint:bottomLeft
                 controlPoint:bottomMiddle];
    [path addQuadCurveToPoint:topLeft
                 controlPoint:leftMiddle];
    //设置阴影路径
     _imageView1.layer.shadowPath = path.CGPath;

ok！