How do I draw a shadow under a UIView

Question

I m trying to draw a shadow under the bottom edge of a UIView in Cocoa Touch  I understand that I should use CGContextSetShadow   to draw the shadow  but the Quartz 2D programming guide is a little vague    Save the graphics state  Call the function CGContextSetShadow  passing the appropriate values  Perform all the drawing to which you want to apply shadows  Restore the graphics state   I ve tried the following in a UIView subclass   -  void drawRect  CGRect rect       CGContextRef currentContext   UIGraphicsGetCurrentContext        CGContextSaveGState currentContext       CGContextSetShadow currentContext  CGSizeMake -15  20   5       CGContextRestoreGState currentContext        super drawRect  rect         but this doesn t work for me and I m a bit stuck about  a  where to go next and  b  if there s anything I need to do to my UIView to make this work

User · Answer

A by far easier approach is to set some layer attributes of the view on initialization:

self.layer.masksToBounds = NO;
self.layer.shadowOffset = CGSizeMake(-15, 20);
self.layer.shadowRadius = 5;
self.layer.shadowOpacity = 0.5;

You need to import QuartzCore.

#import <QuartzCore/QuartzCore.h>

User · Answer

For fellow Xamarians  the Xamarin iOS C  version of the answer would look like the following   public override void DrawRect CGRect area  UIViewPrintFormatter formatter        CGContext currentContext   UIGraphics GetCurrentContext        currentContext SaveState        currentContext SetShadow new CGSize -15  20   5       base DrawRect area  formatter       currentContext RestoreState                        The main difference is that you acquire an instance of CGContext on which you directly call the appropriate methods

User · Answer

I use this as part of my utils  With this we can not only set shadow but also can get a rounded corner for any UIView  Also you could set what color shadow you prefer  Normally black is preferred but sometimes  when the background is non-white you might want something else  Here s what I use -  in utils m    void roundedLayer  CALayer   viewLayer                radius  float r                shadow  BOOL s        viewLayer setMasksToBounds YES        viewLayer setCornerRadius r                viewLayer setBorderColor  RGB 180  180  180  CGColor         viewLayer setBorderWidth 1 0f       if s                 viewLayer setShadowColor  RGB 0  0  0  CGColor             viewLayer setShadowOffset CGSizeMake 0  0             viewLayer setShadowOpacity 1            viewLayer setShadowRadius 2 0             return      To use this we need to call this -  utils roundedLayer yourview layer radius 5 0f shadow YES

User · Answer

Swift 3 extension UIView       func installShadow             layer cornerRadius   2         layer masksToBounds   false         layer shadowColor   UIColor black cgColor         layer shadowOffset   CGSize width  0  height  1          layer shadowOpacity   0 45         layer shadowPath   UIBezierPath rect  bounds  cgPath         layer shadowRadius   1 0

User · Answer

Sketch Shadow Using IBDesignable and IBInspectable in Swift 4     HOW TO USE IT        SKETCH AND XCODE SIDE BY SIDE        CODE    IBDesignable class ShadowView  UIView         IBInspectable var shadowColor  UIColor            get               if let color   layer shadowColor                   return UIColor cgColor  color                            return nil                   set               if let color   newValue                   layer shadowColor   color cgColor               else                   layer shadowColor   nil                                     IBInspectable var shadowOpacity  Float           get               return layer shadowOpacity                   set               layer shadowOpacity   newValue                       IBInspectable var shadowOffset  CGPoint           get               return CGPoint x  layer shadowOffset width  y layer shadowOffset height                    set               layer shadowOffset   CGSize width  newValue x  height  newValue y                          IBInspectable var shadowBlur  CGFloat           get               return layer shadowRadius                   set               layer shadowRadius   newValue   2 0                       IBInspectable var shadowSpread  CGFloat   0           didSet               if shadowSpread    0                   layer shadowPath   nil               else                   let dx   -shadowSpread                 let rect   bounds insetBy dx  dx  dy  dx                  layer shadowPath   UIBezierPath rect  rect  cgPath                                      OUTPUT

User · Answer

Simple and clean solution using Interface Builder  Add a file named UIView swift in your project  or just paste this in any file     import UIKit   IBDesignable extension UIView           The color of the shadow  Defaults to opaque black  Colors created       from patterns are currently NOT supported  Animatable          IBInspectable var shadowColor  UIColor            set               layer shadowColor   newValue  CGColor                   get               if let color   layer shadowColor                   return UIColor CGColor color                            else                   return nil                                       The opacity of the shadow  Defaults to 0  Specifying a value outside the        0 1  range will give undefined results  Animatable          IBInspectable var shadowOpacity  Float           set               layer shadowOpacity   newValue                   get               return layer shadowOpacity                         The shadow offset  Defaults to  0  -3   Animatable          IBInspectable var shadowOffset  CGPoint           set               layer shadowOffset   CGSize width  newValue x  height  newValue y                    get               return CGPoint x  layer shadowOffset width  y layer shadowOffset height                          The blur radius used to create the shadow  Defaults to 3  Animatable          IBInspectable var shadowRadius  CGFloat           set               layer shadowRadius   newValue                   get               return layer shadowRadius                     Then this will be available in Interface Builder for every view in the Utilities Panel   Attributes Inspector      You can easily set the shadow now   Notes   - The shadow won t appear in IB  only at runtime   - As Mazen Kasser said     To those who failed in getting this to work       make sure Clip Subviews  clipsToBounds  is not enabled

User · Answer

You can use this Extension to add shadow  extension UIView        func addShadow offset  CGSize  color  UIColor  radius  CGFloat  opacity  Float                layer masksToBounds   false         layer shadowOffset   offset         layer shadowColor   color cgColor         layer shadowRadius   radius         layer shadowOpacity   opacity          let backgroundCGColor   backgroundColor  cgColor         backgroundColor   nil         layer backgroundColor    backgroundCGColor           you can call it like  your Custom View addShadow offset  CGSize width  0  height  1   color  UIColor black  radius  2 0  opacity  1 0

User · Answer

In your current code  you save the GState of the current context  configure it to draw a shadow    and the restore it to what it was before you configured it to draw a shadow  Then  finally  you invoke the superclass s implementation of drawRect     Any drawing that should be affected by the shadow setting needs to happen after   CGContextSetShadow currentContext  CGSizeMake -15  20   5     but before  CGContextRestoreGState currentContext     So if you want the superclass s drawRect  to be  wrapped  in a shadow  then how about if you rearrange your code like this   -  void drawRect  CGRect rect       CGContextRef currentContext   UIGraphicsGetCurrentContext        CGContextSaveGState currentContext       CGContextSetShadow currentContext  CGSizeMake -15  20   5        super drawRect  rect       CGContextRestoreGState currentContext

User · Answer

Swift 3  self paddingView layer masksToBounds   false self paddingView layer shadowOffset   CGSize width  -15  height  10  self paddingView layer shadowRadius   5 self paddingView layer shadowOpacity   0 5

User · Answer

All Answer all well but I want to add one more point   If you encounter a problem when you have table cells  Deque a new cell there is a mismatch in shadow so in this case  you need to place your shadow code in a layoutSubviews method so that it will behave nicely in all conditions   - void layoutSubviews       super layoutSubviews         self contentView setNeedsLayout        self contentView layoutIfNeeded        VPShadow applyShadowView self       or in ViewControllers for specific view place shadow code inside the following method so that it s work well  - void viewDidLayoutSubviews       super viewDidLayoutSubviews         self viewShadow layoutIfNeeded        VPShadow applyShadowView self viewShadow       I have modified my shadow implementation for new devs for more generalized form ex         brief Add shadow to a view     param layer CALayer of the view         void applyShadowOnView  CALayer   layer OffsetX  CGFloat x OffsetY  CGFloat y blur  CGFloat radius opacity  CGFloat alpha RoundingCorners  CGFloat cornerRadius      UIBezierPath  shadowPath    UIBezierPath bezierPathWithRoundedRect layer bounds cornerRadius cornerRadius       layer masksToBounds   NO      layer shadowColor    UIColor blackColor  CGColor      layer shadowOffset   CGSizeMake x y     shadow x and y     layer shadowOpacity   alpha      layer shadowRadius   radius    blur effect     layer shadowPath   shadowPath CGPath

User · Answer

You can try this      you can play with the values  The shadowRadius dictates the amount of blur  shadowOffset dictates where the shadow goes      Swift 2 0   let radius  CGFloat   demoView frame width   2 0   change it to  height if you need spread for height let shadowPath   UIBezierPath rect  CGRect x  0  y  0  width  2 1   radius  height  demoView frame height     Change 2 1 to amount of spread you need and for height replace the code for height  demoView layer cornerRadius   2 demoView layer shadowColor   UIColor blackColor   CGColor demoView layer shadowOffset   CGSize width  0 5  height  0 4     Here you control x and y demoView layer shadowOpacity   0 5 demoView layer shadowRadius   5 0   Here your control your blur demoView layer masksToBounds    false demoView layer shadowPath   shadowPath CGPath      Swift 3 0   let radius  CGFloat   demoView frame width   2 0   change it to  height if you need spread for height  let shadowPath   UIBezierPath rect  CGRect x  0  y  0  width  2 1   radius  height  demoView frame height      Change 2 1 to amount of spread you need and for height replace the code for height  demoView layer cornerRadius   2 demoView layer shadowColor   UIColor black cgColor demoView layer shadowOffset   CGSize width  0 5  height  0 4     Here you control x and y demoView layer shadowOpacity   0 5 demoView layer shadowRadius   5 0   Here your control your blur demoView layer masksToBounds    false demoView layer shadowPath   shadowPath cgPath      Example with spread        To create a basic shadow        demoView layer cornerRadius   2     demoView layer shadowColor   UIColor blackColor   CGColor     demoView layer shadowOffset   CGSizeMake 0 5  4 0     Here your control your spread     demoView layer shadowOpacity   0 5      demoView layer shadowRadius   5 0   Here your control your blur      Basic Shadow example in Swift 2 0

User · Answer

self layer masksToBounds   NO  self layer cornerRadius   8     if you like rounded corners self layer shadowOffset   CGSizeMake -15  20   self layer shadowRadius   5  self layer shadowOpacity   0 5    This will slow down the application   Adding the following line can improve performance as long as your view is visibly rectangular   self layer shadowPath    UIBezierPath bezierPathWithRect self bounds  CGPath

User · Answer

Same solution  but just to remind you  You can define the shadow directly in the storyboard   Ex

User · Answer

To those who failed in getting this to work  As myself   after trying all the answers here  just make sure Clip Subviews is not enabled at the Attributes inspector

User · Answer

You can use my utility function created for shadow and corner radius as below   -  void addShadowWithRadius  CGFloat shadowRadius withShadowOpacity  CGFloat shadowOpacity withShadowOffset  CGSize shadowOffset withShadowColor  UIColor   shadowColor withCornerRadius  CGFloat cornerRadius withBorderColor  UIColor   borderColor withBorderWidth  CGFloat borderWidth forView  UIView   view          drop shadow      view layer setShadowRadius shadowRadius        view layer setShadowOpacity shadowOpacity        view layer setShadowOffset shadowOffset        view layer setShadowColor shadowColor CGColor           border radius      view layer setCornerRadius cornerRadius           border      view layer setBorderColor borderColor CGColor        view layer setBorderWidth borderWidth       Hope it will help you

User · Answer

If you would like to use StoryBoard and wouldnt like to keep typing in runtime attributes  you can easily create an extension to views and make them usable in storyboard   Step 1  create extension  extension UIView     IBInspectable var shadowRadius  CGFloat       get           return layer shadowRadius           set           layer shadowRadius   newValue           IBInspectable var shadowOpacity  Float       get           return layer shadowOpacity           set           layer shadowOpacity   newValue           IBInspectable var shadowOffset  CGSize       get           return layer shadowOffset           set           layer shadowOffset   newValue           IBInspectable var maskToBound  Bool       get           return layer masksToBounds           set           layer masksToBounds   newValue             step 2  you can now use these attributes in storyboard

[iphone] How do I draw a shadow under a UIView?

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