Drop shadow in ios

问题:

How to drop an object shadow in iOS?

My object is UIImageView and i want to drop an elliptical shadow.Please refer image for reference.

回答1:

Better you use another image for showing shadow. Use blur image or change alpha of the imageview.

Or if you want to do it programmatically, try it:

Obj c:

//create elliptical shadow for image through UIBezierPath
CGRect ovalRect = CGRectMake(0.0f, _imageView.frame.size.height + 10, _imageView.frame.size.width, 15);
UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:ovalRect];

 //applying shadow to path
 _imageView.layer.shadowColor = kShadowColor.CGColor;
 _imageView.layer.shadowOffset = CGSizeMake(0.0, 0.0);
 _imageView.layer.shadowOpacity = 1.0;
 _imageView.layer.shadowRadius = 3.0;
 _imageView.layer.shadowPath = path.CGPath;

Swift :

//create elliptical shdow forimage through UIBezierPath
var ovalRect = CGRectMake(0.0, imageView.frame.size.height + 10, imageView.frame.size.width, 15)
var path = UIBezierPath(ovalInRect: ovalRect)

//applying shadow to path
imageView.layer.shadowColor = UIColor(white: 0.0, alpha: 0.5).CGColor
 imageView.layer.shadowOffset = CGSizeMake(0.0, 0.0)
imageView.layer.shadowOpacity = 1.0
imageView.layer.shadowRadius = 3.0
imageView.layer.shadowPath = path.CGPath

Output:

Taken from http://www.innofied.com/implementing-shadow-ios/ and also have a look to know more: UIView with rounded corners and drop shadow?

回答2:

You can use CAShapeLayer like this:

Objective-C:

// init CAShapeLayer
CAShapeLayer *shadowLayer = [CAShapeLayer layer];
shadowLayer.frame = CGRectMake(CGRectGetMinX(_imageView.frame), CGRectGetMaxY(_imageView.frame), _imageView.frame.size.width, _imageView.frame.size.height);
shadowLayer.path = [UIBezierPath bezierPathWithOvalInRect:shadowLayer.bounds].CGPath;
shadowLayer.fillColor = [UIColor colorWithWhite:0 alpha:0.02].CGColor;
shadowLayer.lineWidth = 0;
[self.view.layer addSublayer: shadowLayer];

Swift 3

let shadowLayer = CAShapeLayer()
shadowLayer.frame = CGRect(x: imageView.frame.minX, y: imageView.frame.maxY, width: imageView.frame.width, height: imageView.frame.height * 0.25)
shadowLayer.path = UIBezierPath(ovalIn: shadowLayer.bounds).cgPath
shadowLayer.fillColor = UIColor(white: 0, alpha: 0.02).cgColor
shadowLayer.lineWidth = 0
view.layer.addSublayer(shadowLayer)

Output: