Removes the need to copy-paste stanzas from other files anymore as we'll rely on #4478 to generate the correct stanza for us instead.
This was an automated change generated by running a find-and-replace regular expression:
```
/\*
Copyright ([0-9]+)-present the Material Components for iOS authors\. All Rights Reserved\.
Licensed under the Apache License, Version 2\.0 \(the "License"\);
you may not use this file except in compliance with the License\.
You may obtain a copy of the License at
http://www\.apache\.org/licenses/LICENSE-2\.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied\.
See the License for the specific language governing permissions and
limitations under the License\.
\*/
```
```
/\*
Copyright ([0-9]+)-present the Material Components for iOS authors\. All Rights Reserved\.
Licensed under the Apache License, Version 2\.0 \(the "License"\);
you may not use this file except in compliance with the License\.
You may obtain a copy of the License at
http://www\.apache\.org/licenses/LICENSE-2\.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied\.
See the License for the specific language governing permissions and
limitations under the License\.
\*/
```
```
/\*
Copyright ([0-9]+)-present the Material Components for iOS authors\. All Rights Reserved\.
Licensed under the Apache License, Version 2\.0 \(the "License"\);
you may not use this file except in compliance with the License\.
You may obtain a copy of the License at
http://www\.apache\.org/licenses/LICENSE-2\.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied\.
See the License for the specific language governing permissions and
limitations under the License\.
\*/
```
```
// Copyright $1-present the Material Components for iOS authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
```
This is the first part of a two-part change that addresses the behavior outlined in https://github.com/material-components/material-components-ios/issues/4104. The second part will expose a similar behavior in the AppBar component.
---
This PR introduces a new top safe area inset behavior to the flexible header view, gated behind the runtime flag `inferTopSafeAreaInsetFromViewController`.
When this behavior is enabled, the flexible header will no longer attempt to infer the top safe area inset from the device's insets using `MDCDeviceTopSafeAreaInset`. Instead, it will infer the top safe area inset from the view controller ancestry of the flexible header view controller.
This new behavior addresses a number of issues related to safe area insets, namely:
- https://github.com/material-components/material-components-ios/issues/4104 (incorrect insets when shown in a popover or modal dialog on iPad).
- Flexible headers can now be used in app extensions.
- The flexible header now properly reacts to status bar visibility changes.
### New feature: top safe area guide
This change introduces a new layout guide that can be used to position content within the flexible header view while respecting the top safe area insets. The `topSafeAreaGuide` API is available on the MDCHeaderView instance of the flexible header view controller and supports iOS 8 and up. An example of its usage to align a view to the bottom of the flexible header's top safe area guide:
```
[NSLayoutConstraint constraintWithItem:self.titleLabel
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.fhvc.headerView.topSafeAreaGuide
attribute:NSLayoutAttributeBottom
multiplier:1.0
constant:0]
```
The new layout guide works whether `inferTopSafeAreaInsetFromViewController` is enabled or disabled.
### Additional information
If using `MDCFlexibleHeaderContainerViewController`, this new behavior is now enabled by default.
The new behavior (and all of the other "new" behaviors) have been enabled on every FlexibleHeader example.
### Results
A screenshot of the result of this API once enabled on the App Bar:

### Architecture
This change builds off of the foundation introduced in 80fd217f766e0f5be6a3bc6bef5923f231721f9d. As part of that change, we made it possible to modify a given view controller's top layout guide such that it equalled the top safe area insets + the flexible header height. Unfortunately, that change was still limited by the fact that the flexible header always assumed that it was placed as a full-screen view.
With the new `inferTopSafeAreaInsetFromViewController` behavior, we are able to extract the top safe area inset from our view controller ancestry instead. We can then combine this extracted value with our flexible header's height before ultimately writing that to the target top layout guide. This flow is roughly shown in the following diagram:

In order to implement this flow we needed to implement two things:
1. A mechanism by which we could infer the root-most ancestral view controller from which we could extract safe area insets.
2. A mechanism by which we could be notified every time that root view controller's safe area insets changed.
The first mechanism is implemented by `fhv_inferTopSafeAreaSourceViewController` as a simple ancestral traversal. We walk up the view controller tree from the flexible header's parent until we run out of ancestors. There is some nuance to this algorithm, in that we need to ensure that our ancestor isn't our `topLayoutGuideViewController` or we risk creating an infinite loop. If we encounter such a situation we attempt to break the loop by walking up the topLayoutGuideViewController's ancestry instead, but at this point it's very likely we won't have a viable ancestor and we'll throw an assertion if/when we can't find a viable ancester.
With an ancestor in hand, we then determine whether to KVO observe `topLayoutGuide` or `safeAreaInsets` based on whether we're running pre-iOS 11 or iOS 11+, respectively.
KVO then informs us of any changes to the top safe area insets, which we can then propagate through the flexible header view and eventually on to the top layout guide (if `topLayoutGuideAdjustmentEnabled` is also enabled).
All examples now have at least the required `+catalogBreadcrumbs` and `+catalogIsPrimaryDemo`. All examples in the same breadcrumbs path have only one primary demo. There should be only one `-catalogDescription` attached to the primary demo.
Closes#1897
Discussed merge with Ian offline. Issues with Travis CI may be resolved once the PR is merged.
* Add color to tiles.
* Add theming to catalog
* Update text field tile.
* Implementation method signatures should match those in header.
* Update MDCDrawFunc typedef
* Pass color scheme through NSNotification
* Add component theming
* Add tabbar themer
* Update tab example to use UIAppearance
* Theme sliders based on UIAppearance proxy
* Allow any class conforming to MDCColorScheme
* Override navigation bar color theme for imagery example.
* Update AppBar and ButtonBar color theming
* Update button bar themer comment
* Update button theming
* Remove theme imports where not necessary.
* Fix case of private
* Replace MDC all icons
* Update border
* Replace MDCActionExtension icon with new logo
* Update all headers to be white on black
* Make Catalog greyscale to match Material’s style.
* Fix collection tile
* Update all headers to be white on black
* Make Catalog greyscale to match Material’s style.
* Fix collection tile
* WIP: Updating TabBar example to use black/green theme.
* WIP: Monochoroming all examples.
* Switch MDC Catalog to a black and white theme (#1355)
* Replace MDC all icons
* Update border
* Replace MDCActionExtension icon with new logo
* Update all headers to be white on black
* Make Catalog greyscale to match Material’s style.
* Fix collection tile
* Update all headers to be white on black
* Make Catalog greyscale to match Material’s style.
* Fix collection tile
* Fix floats
* Make Catalog greyscale to match Material’s style.
* More black and whiting
* WIP: Snackbar and global style
* Simplify snack bar examples.
* Page control
We can credit any contributor who would like to be credited this way, by adding them on request to the AUTHORS file. The copyright statement changes are required for this to work. Note that this has...
Summary:
We can credit any contributor who would like to be credited this way, by adding them on request to the AUTHORS file. The copyright statement changes are required for this to work. Note that this has no legal change, since the contributors always retained their copyright despite the copyright notice, but it's a nice acknowledgement.
Changed copyright statement to include non-Google authors.
Command run:
find * \( -name '*\.m' -or -name '*\.h' -or -name '*\.swift' \) -and -not \( -path 'scripts/external*' -name Pods \) -print0 | xargs -0 sed -i '' 's/Copyright \(.*\) Google Inc/Copyright \1 the Material Components for iOS authors/'
Added non-source files.
Command run:
grep -Rl 'Copyright .* Google Inc' * --exclude-dir scripts/external --null | xargs -0 sed -i '' 's/Copyright \(.*\) Google Inc/Copyright \1 the Material Components for iOS authors/'
Reviewers: featherless, O1 Material components iOS, randallli
Reviewed By: O1 Material components iOS, randallli
Tags: #material_components_ios
Differential Revision: http://codereview.cc/D1415
Summary: The catalog now calls init on view controllers to initialize them. This does not chain to initWithNibName.
Reviewers: #mdc_ios_owners, junius
Reviewed By: #mdc_ios_owners, junius
Projects: #material_components_ios
Differential Revision: http://codereview.cc/D689
Summary: Recreated and updated 'Configurator' example for new example schemes and did some cleanup on 'Typical Use'
Reviewers: #mdc_ios_owners, featherless
Reviewed By: #mdc_ios_owners, featherless
Subscribers: featherless
Projects: #material_components_ios
Differential Revision: http://codereview.cc/D460
Summary: This is the 'typical use' example for flexible header. It's been changed to have less content and styling that matches the new catalog app. Universal and all rotations.
Reviewers: featherless, #mdc_ios_owners
Reviewed By: featherless, #mdc_ios_owners
Subscribers: featherless
Projects: #material_components_ios
Differential Revision: http://codereview.cc/D430
Summary: See `FlexibleHeaderTypicalUseExample.m` to learn how we expect the Flexible Header to be used.
Reviewers: ajsecord, #mdc_ios_owners
Reviewed By: ajsecord, #mdc_ios_owners
Subscribers: ajsecord
Projects: #material_components_ios
Differential Revision: http://codereview.cc/D196
Summary:
This simplifies the examples for each of these components.
The other components have a few extra features that may take a bit more time to migrate over,
notably:
- Swift (ShadowLayer)
- Resources (SpritedAnimationView)
- Unit and UI tests (Switch, Typography)
Reviewers: junius, randallli, #mdc_ios_owners, ajsecord
Reviewed By: #mdc_ios_owners, ajsecord
Subscribers: ajsecord
Projects: #material_components_ios
Differential Revision: http://codereview.cc/D124