Cards contain content and actions about a single subject. They can be used standalone, or as part of a list. Cards are meant to be interactive, and aren't meant to be be used solely for style purposes.
Cards provides two different versions, MDCCard inheriting from UIControl and MDCCardCollectionCell inheriting from UICollectionViewCell.
A card's state determines its visual styling.
When treated as a UIControl (MDCCard), it has a default styling (UIControlStateNormal), and a highlighted styling (UIControlStateHighlighted) when interacted with.
When treated as a UICollectionViewCell (MDCCardCollectionCell), it has a default styling (MDCCardCellStateNormal), a highlighted styling (MDCCardCellStateHighlighted), and lastly a selected styling (MDCCardCellStateSelected).
Customization to the card is exposed via its API either in MDCCard or MDCCardCollectionCell. Currently the card consists of these customizations:
(MDCCardCollectionCell customization only):
An MDCCard can be added and used as you would add any UIView or UIControl, if manually in code, or through Interface Builder.
An MDCCardCollectionCell can be added, used, and reused as a UICollectionViewCell, if manually in code, or through Interface Builder.
MDCCardThemer exposes apis to theme MDCCard and MDCCardCollectionCell instances as either a default or outlined variant. An outlined variant behaves identically to a default styled card, but differs in its coloring and in that it has a stroked border. Use ‘applyScheme:toCard:’ to style an instance with default values and ‘applyOutlinedVariantWithScheme:toCard:’ to style an instance with the outlined values.
MDCCard subclasses UIControl and provides a simple class for developers to subclass and create custom cards with ink, shadows, corner radius, and stroke matching the Material spec.
MDCCard uses the highlighted property that is built-in in UIControl and the UIControlState to move between states.
MDCCardCollectionCell subclasses UICollectionViewCell and provides a simple collection view cell for developers to use in their collections with ink, shadows, corner radius, and stroke matching the Material spec.
MDCCardCollectionCell uses the selected property that is built-in in UICollectionViewCell and has its own MDCCardCellState to keep track of the current state it is in.
Add the following to your Podfile:
pod 'MaterialComponents/Cards'
Then, run the following command:
pod install
To import the component:
import MaterialComponents.MaterialCards
#import "MaterialCards.h"
MDCCard can be used like a regular UIView.
let card = MDCCard() // Create, position, and add content views: let imageView = UIImageView() card.addSubview(imageView)
MDCCard *card = [[MDCCard alloc] init]; // Create, position, and add content views: UIImageView *imageView = [[UIImageView alloc] init]; [card addSubview:imageView];
Use MDCCardCollectionCell as a base class for your custom collection view cell
collectionView.register(MDCCardCollectionCell.self, forCellWithReuseIdentifier: "Cell") func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell { let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as! MDCCardCollectionCell // If you wanted to have the card show the selected state when tapped // then you need to turn isSelectable to true, otherwise the default is false. cell.isSelectable = true cell.selectedImageTintColor = .blue cell.cornerRadius = 8 cell.setShadowElevation(6, for: .selected) cell.setShadowColor(UIColor.black, for: .highlighted) return cell }
[self.collectionView registerClass:[MDCCardCollectionCell class] forCellWithReuseIdentifier:@"Cell"]; - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath { MDCCardCollectionCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"Cell" forIndexPath:indexPath]; // If you wanted to have the card show the selected state when tapped // then you need to turn selectable to true, otherwise the default is false. [cell setSelectable:YES]; [cell setSelectedImageTintColor:[UIColor blueColor]]; [cell setCornerRadius:8]; [cell setShadowElevation:6 forState:MDCCardCellStateSelected]; [cell setShadowColor:[UIColor blackColor] forState:MDCCardCellStateHighlighted]; }
You can theme a card with your app's color scheme using the ColorThemer extension.
You must first add the Color Themer extension to your project:
pod 'MaterialComponents/Cards+ColorThemer'
// Step 1: Import the ColorThemer extension import MaterialComponents.MaterialCards_ColorThemer // Step 2: Create or get a color scheme let colorScheme = MDCSemanticColorScheme() // Step 3: Apply the color scheme to your component MDCCardsColorThemer.applySemanticColorScheme(colorScheme, to: component)
// Step 1: Import the ColorThemer extension #import "MaterialCards+ColorThemer.h" // Step 2: Create or get a color scheme id<MDCColorScheming> colorScheme = [[MDCSemanticColorScheme alloc] initWithDefaults:MDCColorSchemeDefaultsMaterial201804]; // Step 3: Apply the color scheme to your component [MDCCardsColorThemer applySemanticColorScheme:colorScheme toCard:component];
You can theme a card with your app's shape scheme using the ShapeThemer extension.
You must first add the ShapeThemer extension to your project:
pod 'MaterialComponents/Cards+ShapeThemer'
// Step 1: Import the ShapeThemer extension import MaterialComponents.MaterialCards_ShapeThemer // Step 2: Create or get a shape scheme let shapeScheme = MDCShapeScheme() // Step 3: Apply the shape scheme to your component MDCCardsShapeThemer.applyShapeScheme(shapeScheme, to: component)
// Step 1: Import the ShapeThemer extension #import "MaterialCards+ShapeThemer.h" // Step 2: Create or get a shape scheme id<MDCShapeScheming> shapeScheme = [[MDCShapeScheme alloc] init]; // Step 3: Apply the shape scheme to your component [MDCCardsShapeThemer applyShapeScheme:shapeScheme toCard:component];
To help ensure your cards are accessible to as many users as possible, please be sure to review the following recommendations:
Since assistive technologies visit all cards in a collection in a sequential order, it is often easier to distinguish between elements that belong to different cards by aggregating all the card‘s information so the card is read as a single sentence.
This can be done by setting an appropriate accessibilityLabel for the card. Additionally, set the card’s isAccessibilityElement to true. Cards are a container element and setting isAccessibiltyElement for a container turns off individually selecting its subelements.
Swift
card.isAccessibilityElement = true card.accessibilityLabel = "Location \(userLocation.name) is popular with users " + "who enjoy \(userLocation.popularActivityMatchingUserProfile(userProfile))"
Objective-C
card.isAccessibilityElement = YES; card.accessibilityLabel = [NSString stringWithFormat:@"Location %@ is popular with users who enjoy %@", userLocation.name, userLocation.popularActivityMatchingUserProfile(userProfile)];
Nested elements in MDCCards are available to assistive technologies without additional customization, however additional setup may be needed to accommodate special scenarios, such as:
Images that have additional context beyond text that is already presented on the card.
For example, news article images can benefit from an accessibilityLabel describing their content.
Swift
articleImageView.isAccessibilityElement = true articleImageView.accessibilityLabel = "Event or scene description"
Objective-C
articleImageView.isAccessibilityElement = YES; articleImageView.accessibilityLabel = @"Event or scene description";
Star or rating images should have an accessibilityLabel describing its purpuse and an accessibilityValue describing the rating value.
Swift
ratingView.isAccessibilityElement = true ratingView.accessibilityLabel = "Average customer rating, out of " + "\(MDCProductRating.maximumValue) stars" ratingView.accessibilityValue = (String)product.averageRating
Objective-C
ratingView.isAccessibilityElement = YES; ratingView.accessibilityLabel = [NSString stringWithFormat:@"Average customer" + " rating, out of %d stars", MDCProductRating.maximumValue]; ratingView.accessibilityValue = @(product.averageRating).stringValue;
Primary content or actions that appear lower on the screen will be read last by assistive technologies, sometimes after longer or non-primary content. To change the order, or group elements together, you can make the card an accessibility container by adopting the UIAccessibilityContainer protocol. Grouping and order is controlled by creating as many UIAccessibilityElement elements as needed, and returning them in the desired order.