在ios中投下阴影

Question

如何在iOS中投下物体阴影？

我的对象是UIImageView，我想放下一个椭圆形阴影。请参考图像以供参考。

Answer 1

更好的是您使用另一个图像来显示阴影。使用模糊图像或更改imageview的alpha。

或者，如果你想以编程方式做到这一点，试试吧：

的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; 

斯威夫特：

//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 

输出：

从http://www.innofied.com/implementing-shadow-ios/两者也看看了解更多：UIView with rounded corners and drop shadow?

Answer 2

您可以使用CAShapeLayer这样的：

的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]; 

斯威夫特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) 

输出：