How can I add shadow to a circle UIImageView or UI

问题:

I am trying to make a circle UIImageView, and it works. Below is the way I use to make it:

[self.pic.layer setMasksToBounds:YES];
[self.pic.layer setCornerRadius:50.0];

I would like to add some shadow to the UIImageView. The below code does add some shadow to my image view, however, the image view changes back to square shape. Can someone give me some pointers to solve this problem? Below is the code I use to add the shadow:

self.pic.layer.shadowColor = [UIColor purpleColor].CGColor;
self.pic.layer.shadowOffset = CGSizeMake(0, 1);
self.pic.layer.shadowOpacity = 1;
self.pic.layer.shadowRadius = 1.0;
self.pic.clipsToBounds = NO;

回答1:

Use the CALayer's shadowPath property and add a UIBezierPath with rounded rect

self.pic.layer.shadowPath = [UIBezierPath bezierPathWithRoundedRect:self.pic.frame cornerRadius:50.0].CGPath;

EDIT

For a square-ish image view this technique does not work directly because, as you said, the image view goes back to square. Reason: You set clipsToBounds = NO to show the shadow which removes the clipping for corner radius, where imageView is subview of container.

Workaround:
Add your imageview in a container view and then apply the layer shadow to this container. Following is the code I tried.

[self.imageView.layer setCornerRadius:60.0];
[self.imageView.layer setMasksToBounds:YES];
self.imageView.clipsToBounds = YES;

self.container.backgroundColor = [UIColor clearColor];
self.container.layer.shadowColor = [UIColor blackColor].CGColor;
self.container.layer.shadowOffset = CGSizeMake(5,15);
self.container.layer.shadowOpacity = 0.5;
self.container.layer.shadowRadius = 2.0;
self.container.layer.shadowPath = [UIBezierPath bezierPathWithRoundedRect:self.container.bounds cornerRadius:100.0].CGPath;

The resultant effect is as shown in the screenshot,

Hope that helps!

回答2:

In case anyone looks for Swift 3 or 4 working solution:

    let imageSize: CGFloat = 64.0

    // Create a container which has a shadow
    let imageCotainer = UIView(frame: CGRect(x: 0, y: 0, width: imageSize, height: imageSize))
    imageCotainer.clipsToBounds = false
    imageCotainer.layer.shadowColor = UIColor.black.cgColor
    imageCotainer.layer.shadowOpacity = 0.2
    imageCotainer.layer.shadowOffset = CGSize(width: 0, height: 1)
    imageCotainer.layer.shadowRadius = 2

    // Create an image view that will be inserted into the container view
    let imageView = UIImageView(frame: imageCotainer.bounds)
    imageView.image = yourImage
    imageView.clipsToBounds = true
    let cornerRadius = imageView.frame.height / 2
    imageView.layer.cornerRadius = cornerRadius

    // Draw a shadow
    imageCotainer.layer.shadowPath = UIBezierPath(roundedRect: imageCotainer.bounds, cornerRadius: cornerRadius).cgPath
    // Add image into container
    imageCotainer.addSubview(imageView)

Sometimes you also need to set constraints for image inside of the container, but it may work without it too in some cases. But if it's not, add this:

    // Set constraints for the image inside the container view
    imageView.translatesAutoresizingMaskIntoConstraints = false
    imageView.topAnchor.constraint(equalTo: imageCotainer.topAnchor).isActive = true
    imageView.leftAnchor.constraint(equalTo: imageCotainer.leftAnchor).isActive = true
    imageView.rightAnchor.constraint(equalTo: imageCotainer.rightAnchor).isActive = true
    imageView.bottomAnchor.constraint(equalTo: imageCotainer.bottomAnchor).isActive = true
    imageView.heightAnchor.constraint(equalToConstant: imageSize).isActive = true
    imageView.widthAnchor.constraint(equalToConstant: imageSize).isActive = true

回答3:

Without a container but with a background view here is my 2 cents

As a swift 2.2 extension

    image?.applyCircleShadow(5, shadowOpacity: 1)

extension UIView {
    func applyCircleShadow(shadowRadius: CGFloat = 2,
                           shadowOpacity: Float = 0.3,
                           shadowColor: CGColor = UIColor.blackColor().CGColor,
                           shadowOffset: CGSize = CGSize.zero) {
        layer.cornerRadius = frame.size.height / 2
        layer.masksToBounds = false
        layer.shadowColor = shadowColor
        layer.shadowOffset = shadowOffset
        layer.shadowRadius = shadowRadius
        layer.shadowOpacity = shadowOpacity
    }
}
extension UIImageView {
    override func applyCircleShadow(shadowRadius: CGFloat = 2,
                                    shadowOpacity: Float = 0.3,
                                    shadowColor: CGColor = UIColor.blackColor().CGColor,
                                    shadowOffset: CGSize = CGSize.zero) {

        // Use UIImageView.hashvalue as background view tag (should be unique)
        let background: UIView = superview?.viewWithTag(hashValue) ?? UIView()
        background.frame = frame
        background.backgroundColor = backgroundColor
        background.tag = hashValue
        background.applyCircleShadow(shadowRadius, shadowOpacity: shadowOpacity, shadowColor: shadowColor, shadowOffset: shadowOffset)
        layer.cornerRadius = background.layer.cornerRadius
        layer.masksToBounds = true
        superview?.insertSubview(background, belowSubview: self)
    }
}

回答4:

I might be a bit late.

You can easily set the required attributes on the storyboard attribute inspector.

The result would be something like this.

回答5:

I created custom classes (swift 3 or 4) and it works very well :

class RoundShadowImageView: RoundView {

    var imageView = RoundImageView()

    var image: UIImage!  {
        didSet {
            imageView.image = image
        }
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
        addSubview(imageView)
        needsUpdateConstraints()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        addSubview(imageView)
        needsUpdateConstraints()
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        clipsToBounds = false
        layer.shadowColor = UIColor.black.cgColor
        layer.shadowOpacity = 0.1
        layer.shadowOffset = CGSize(width: 0, height: 10)
        layer.shadowRadius = 10
        layer.shadowPath = UIBezierPath(roundedRect: bounds, cornerRadius: frame.height / 2.0).cgPath
    }

    override func updateConstraints() {
        super.updateConstraints()

        imageView.snp.makeConstraints { (make) -> Void in
            make.height.width.equalTo(self)
            make.center.equalTo(self)
        }
    }
}

class RoundImageView: UIImageView {

    override func layoutSubviews() {
        super.layoutSubviews()
        let radius: CGFloat = self.bounds.size.height / 2.0
        layer.cornerRadius = radius
        clipsToBounds = true
    }
}

class RoundView: UIView {

    override func layoutSubviews() {
        super.layoutSubviews()
        let radius: CGFloat = self.bounds.size.height / 2.0
        layer.cornerRadius = radius
        clipsToBounds = true
    }
}

There are 2 classes to make a container and an image view round. And the main class which combines both of them: the one that you'll call.

回答6:

extension UIImageView {
    func addShadow() {
        self.layer.shadowColor = UIColor.black.cgColor
        self.layer.shadowOffset = CGSize(width: 2, height: 5)
        self.layer.shadowOpacity = 0.5
        self.layer.shadowRadius = 1.0
        self.clipsToBounds = false
    }
}
try this code. hope it will help you....