Add shadow to UIView on all sides in Swift 4

I am trying to add a shadow to my UIViews using a custom extension that I created for the UIView class. Here is the code for the extension.

可從User Defined Runtime Attributes 設定三種常見的陰影效果，layer.shadowOpacity，layer.shadowOffset 和layer.shadowRadius。

If you want to add shadow then do this : viewLoginCustom.dropShadow(color: yourColor, opacity: 1, offSet: CGSize.zero, radius: 3, scale: true)

iOS can dynamically generate shadows for any UIView, and these shadows automatically adjust to fit the shape of the item in question.

當處理圖片圓角時，須clipToBounds = true，image view才能把image裁切掉，但shadow是影響在image所以也會被裁切掉。需要同時有cornerRadius與shadow，則 ...

預設值為0，也就是完全透明； 所以如果只是要陰影，並沒有需要客製化的話， 只需要修改shadowOpacity，畫面上就會有offset = [0, -3], radius = 3 的不透明黑色 ...

In this article we're going to look at some of the various effects you can create using shadows, all by manipulating the layer properties.

Add a drop shadow to a UIView. GitHub Gist: instantly share code, notes, and snippets.

All you need to do in order to add a shadow to a UIView object is to set the shadow properties of the view's layer.

layer.shadowOffset = CGSize.init(width: 0, height: 3) layer.shadowColor = UIColor.gray.cgColor layer.shadowRadius = 3 layer.shadowOpacity = 0.4