Andrew Overton 4e245ac6dc [Multiple components] Miscellaneous doc updates
This PR closes out all current doc change requests.

Closes https://github.com/material-components/material-components-ios/pull/10181

COPYBARA_INTEGRATE_REVIEW=https://github.com/material-components/material-components-ios/pull/10181 from andrewoverton:dev-docs-03-15-cherry-pick 00414a4f89e39dfc8d47623ee95e0311db1c7ae7
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<!--docs:
title: Buttons
layout: detail
section: components
excerpt: "iOS Buttons"
iconId:
path: /catalog/buttons/
api_doc_root: true
-->
# Buttons
[Buttons](https://material.io/components/buttons/) allow users to take actions, and make choices, with a single tap.
!["Button on a screen"](assets/buttons_hero.png)
**Contents**
* [Using buttons](#using-buttons)
* [Text button](#text-button)
* [Outlined button](#outlined-button)
* [Contained button](#contained-button)
* [Theming](#theming)
- - -
## Using buttons
### Installing
In order to use Material buttons, first add the `Buttons` subspec to your `Podfile`:
```bash
pod MaterialComponents/Buttons
```
<!--{: .code-renderer.code-renderer--install }-->
Then, run the installer:
```bash
pod install
```
After that, import the relevant target or file and initialize your button.
<!--<div class="material-code-render" markdown="1">-->
#### Swift
```swift
import MaterialComponents.MaterialButtons
let button = MDCButton()
```
#### Objective-C
```objc
#import "MaterialButtons.h"
MDCButton *button = [[MDCButton alloc] init];
```
<!--</div>-->
### Making Buttons accessible
To help ensure your buttons are accessible to as many users as possible, please
be sure to review the following recommendations:
#### Set `-accessibilityLabel`
Set an appropriate
[`accessibilityLabel`](https://developer.apple.com/documentation/uikit/uiaccessibilityelement/1619577-accessibilitylabel)
value if your button does not have a title. This is often the case with Floating
Action Button instances which typically only have an icon.
<!--<div class="material-code-render" markdown="1">-->
#### Swift
```swift
button.accessibilityLabel = "Create"
```
#### Objective-C
```objc
button.accessibilityLabel = @"Create";
```
<!--</div>-->
#### Minimum touch size
Make sure that your buttons have a minimum touch area. The Material spec
for buttons calls for buttons that have a [visual height of
36](https://material.io/design/components/buttons.html#specs)
and that [touch areas should be at least 48 points high and 48
wide](https://material.io/design/layout/spacing-methods.html#touch-click-targets).
#### Set the touch size
To keep a button's visual sizes small with larger touchable areas, set the
`hitAreaInsets` to a negative value. Be careful to maintain sufficient distance
between the button touch targets. This will allow your button to have [a large
enough touch
target](https://material.io/design/layout/spacing-methods.html#touch-click-targets)
while maintaining the desired visual appearance. For more see the [Touch and click
targets](https://material.io/design/layout/spacing-methods.html#touch-click-targets)
in the spec.
<!--<div class="material-code-render" markdown="1">-->
#### Swift
```swift
let buttonVerticalInset =
min(0, -(kMinimumAccessibleButtonSize.height - button.bounds.height) / 2);
let buttonHorizontalInset =
min(0, -(kMinimumAccessibleButtonSize.width - button.bounds.width) / 2);
button.hitAreaInsets =
UIEdgeInsetsMake(buttonVerticalInset, buttonHorizontalInset,
buttonVerticalInset, buttonHorizontalInset);
```
#### Objective-C
```objc
CGFloat verticalInset = MIN(0, -(48 - CGRectGetHeight(button.bounds)) / 2);
CGFloat horizontalInset = MIN(0, -(48 - CGRectGetWidth(button.bounds)) / 2);
button.hitAreaInsets = UIEdgeInsetsMake(verticalInset, horizontalInset, verticalInset, horizontalInset);
```
<!--</div>-->
#### Set the minimum visual size of the button
Set your buttons to have a minimum size. Though there are some exceptions, [Material Buttons
guidelines](https://material.io/design/components/buttons.html#specs)
typically recommend [a minimum height of 36 points and a minimum width of 64
points](https://material.io/design/components/buttons.html#specs).
<!--<div class="material-code-render" markdown="1">-->
#### Swift
```swift
button.minimumSize = CGSize(width: 64, height: 48)
```
#### Objective-C
```objc
button.minimumSize = CGSizeMake(64, 36);
```
<!--</div>-->
#### Using `accessibilityHint`
Apple rarely recommends using the `accessibilityHint` because the label should
already be clear enough to indicate what will happen. Before you consider
setting an `-accessibilityHint` consider if you need it or if the rest of your
UI could be adjusted to make it more contextually clear.
A well-crafted, thoughtful user interface can remove the need for
`accessibilityHint` in most situations. Examples for a selection dialog to
choose one or more days of the week for a repeating calendar event:
- (Good) The dialog includes a header above the list of days reading, "Event
repeats weekly on the following day(s)." The list items do not need
`accessibilityHint` values.
- (Bad) The dialog has no header above the list of days. Each list item
(representing a day of the week) has the `accessibilityHint` value, "Toggles
this day."
**Types**
There are four types of buttons: 1\. [Text button](#text-button) 2\. [Outlined button](#outlined-button) 3\. [Contained button](#contained-button) 4\. Toggle button (*not supported in iOS*)"
![Example of the four button types](assets/buttons_types.png)
All Material buttons are implemented by `MDCButton`, a subclass of [`UIButton`](https://developer.apple.com/documentation/uikit/uibutton).
* [GitHub source](https://github.com/material-components/material-components-ios/blob/develop/components/Buttons/src/MDCButton.h)
## Text button
<img src="assets/ios-text-button.gif" alt="An animated Material Design text button." width="128">
[Text buttons](https://material.io/components/buttons/#text-button) are typically used for less-pronounced actions, including those located in dialogs and cards. In cards, text buttons help maintain an emphasis on card content.
### Text button example
To use a text button use the text button theming method on the `MDCButton` theming extension. For more information on theming extensions see the [Theming section](#theming).
<!--<div class="material-code-render" markdown="1">-->
#### Swift
```swift
button.applyTextTheme(withScheme: containerScheme)
```
#### Objective-C
```objc
[self.button applyTextThemeWithScheme:self.containerScheme];
```
<!--</div>-->
### Anatomy and key properties
A text button has a text label, a transparent container and an optional icon.
![Text button anatomy diagram](assets/text_button_anatomy.png)
1. Text label
1. Container
1. Icon
#### Text label attributes
&nbsp; | Attribute | Related method(s) | Default value
-------------- | ------------------------ | --------------------------------- | -------------
**Text label** | `titleLabel` | `setTitle:forState:`<br/>`titleForState:` | `nil`
**Color** | `titleLabel.textColor` | `setTitleColor:forState:`<br/>`titleColorForState:` | Primary color
**Typography** | `titleLabel.font` | `setFont:` and `font` on `titleLabel` | Button
#### Container attributes
&nbsp; | Attribute | Related method(s) | Default value
---------------- | --------------------- | ---------------------------------------------------------------------------- | -------------
**Color** | `backgroundColor` | `setBackgroundColor:forState:`<br/>`backgroundColorForState`<br/> | `UIColor.clearColor`
**Stroke color** | | `setBorderColor:forState:`<br/>`borderColorForState:` | `nil`
**Stroke width** | | `setBorderWidth:forState:`<br/>`borderWidthForState:` | `0`
**Ripple color** | `inkColor` | `setInkColor`<br/>`inkColor` | Primary color at 12% opacity
#### Icon attributes
&nbsp; | Attribute | Related method(s) | Default value
----------------------------------------------- | ----------------- | --------------------------------------------------------- | -------------
**Icon** | `imageView` | `setImage:forState:`<br/>`imageForState:` | `nil`
**Color** | `imageView.tintColor` | `setImageViewTintColor:forState:`<br/>`imageViewTintColorForState:` | `nil`
## Outlined button
<img src="assets/ios-outlined.gif" alt="An animated Material Design outlined button." width="115">
[Outlined buttons](https://material.io/components/buttons/#outlined-button) are medium-emphasis buttons. They contain actions that are important, but arent the primary action in an app.
### Outlined button example
To achieve an outlined button use the outlined button theming method on the `MDCButton` theming extension. To access the theming extension see the [Theming section](#theming).
<!--<div class="material-code-render" markdown="1">-->
#### Swift
```swift
button.applyOutlinedTheme(withScheme: containerScheme)
```
#### Objective-C
```objc
[self.button applyOutlinedThemeWithScheme:self.containerScheme];
```
<!--</div>-->
### Anatomy and Key properties
An outlined button has a text label, a container, and an optional icon.
![Outlined button anatomy diagram](assets/outlined_button_anatomy.png)
1. Text label
1. Container
1. Icon
#### Text label attributes
&nbsp; | Attribute | Related method(s) | Default value
-------------- | ------------------------ | --------------------------------- | -------------
**Text label** | `titleLabel` | `setTitle:forState:`<br/>`titleForState:` | `nil`
**Color** | `titleLabel.textColor` | `setTitleColor:forState:`<br/>`titleColorForState:` | Primary color
**Typography** | `titleLabel.font` | `setFont:` and `font` on `titleLabel` | Button
#### Container attributes
&nbsp; | Attribute | Related method(s) | Default value
---------------- | --------------------- | ---------------------------------------------------------------------------- | -------------
**Color** | `backgroundColor` | `setBackgroundColor:forState:`<br/>`backgroundColorForState`<br/> | `UIColor.clearColor`
**Stroke color** | | `setBorderColor:forState:`<br/>`borderColorForState:` | On surface color at 12% opacity
**Stroke width** | | `setBorderWidth:forState:`<br/>`borderWidthForState:` | 1
**Ripple color** | `inkColor` | `setInkColor`<br/>`inkColor` | Primary color at 12% opacity
#### Icon attributes
&nbsp; | Attribute | Related method(s) | Default value
----------------------------------------------- | ----------------- | --------------------------------------------------------- | -------------
**Icon** | `imageView` | `setImage:forState:`<br/>`imageForState:` | `nil`
**Color** | `imageView.tintColor` | `setImageViewTintColor:forState:`<br/>`imageViewTintColorForState:` | `nil`
## Contained button
<img src="assets/ios-contained.gif" alt="An animated Material Design contained button." width="128">
[Contained buttons](https://material.io/components/buttons/#contained-button) are high-emphasis, distinguished by their use of elevation and fill. They contain actions that are primary to your app.
### Contained button example
Contained buttons are implemented by `MDCButton`. To achieve a contained button use the contained button theming method on the `MDCButton` theming extension. To access the theming extension see the [Theming section](#theming).
<!--<div class="material-code-render" markdown="1">-->
#### Swift
```swift
button.applyContainedTheme(withScheme: containerScheme)
```
#### Objective-C
```objc
[self.button applyContainedThemeWithScheme:self.containerScheme];
```
<!--</div>-->
### Anatomy and Key properties
A contained button has a text label, a container, and an optional icon.
![Contained button anatomy diagram](assets/contained_button_anatomy.png)
1. Text label
1. Container
1. Icon
#### Text label attributes
&nbsp; | Attribute | Related method(s) | Default value
-------------- | ------------------------ | --------------------------------- | -------------
**Text label** | `titleLabel` | `setTitle:forState:`<br/>`titleForState:` | `nil`
**Color** | `titleLabel.textColor` | `setTitleColor:forState:`<br/>`titleColorForState:` | On primary color
**Typography** | `titleLabel.font` | `setFont:` and `font` on `titleLabel` | Button
#### Container attributes
&nbsp; | Attribute | Related method(s) | Default value
---------------- | --------------------- | ---------------------------------------------------------------------------- | -------------
**Color** | `backgroundColor` | `setBackgroundColor:forState:`<br/>`backgroundColorForState`<br/> | Primary color
**Stroke color** | | `setBorderColor:forState:`<br/>`borderColorForState:` | `nil`
**Stroke width** | | `setBorderWidth:forState:`<br/>`borderWidthForState:` | `nil`
**Ripple color** | `inkColor` | `setInkColor`<br/>`inkColor` | On primary color at 12% opacity
#### Icon attributes
&nbsp; | Attribute | Related method(s) | Default value
----------------------------------------------- | ----------------- | --------------------------------------------------------- | -------------
**Icon** | `imageView` | `setImage:forState:`<br/>`imageForState:` | `nil`
**Color** | `imageView.tintColor` | `setImageViewTintColor:forState:`<br/>`imageViewTintColorForState:` | `nil`
## Theming
You can theme an `MDCButton` to match any of the Material Button styles using theming
extensions. [Learn more about theming extensions](../../../docs/theming.md). Below is a screenshot of Material Buttons with the Material Design Shrine theme:
![Shrine buttons](assets/shrine-buttons.png)
### Buttons theming example
To make use of the theming methods shown in the examples above install the Buttons theming extensions with Cocoapods. First, add the following line to your `Podfile`:
```bash
pod MaterialComponents/Buttons+Theming
```
<!--{: .code-renderer.code-renderer--install }-->
Then run the installer:
```bash
pod install
```
Next, import the Buttons theming target and initialize a button.
<!--<div class="material-code-render" markdown="1">-->
#### Swift
```swift
import MaterialComponents.MaterialButtons
import MaterialComponents.MaterialButtons_Theming
let button = MDCButton()
```
#### Objective-C
```objc
#import "MaterialButtons.h"
#import "MaterialButtons+Theming.h"
MDCButton *button = [[MDCButton alloc] init];
```
<!--</div>-->
From there, use the theming methods from the examples to achieve your preferred button style.