material-components_material-components-ios/components/Snackbar/examples/SnackbarOverlayViewExample.m

// Copyright 2016-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.

#import <UIKit/UIKit.h>

#import "MaterialOverlay.h"
#import "MaterialSnackbar.h"
#import "supplemental/SnackbarExampleSupplemental.h"

static const CGFloat kFABBottomOffset = 24.0f;
static const CGFloat kFABSideOffset = 24.0f;
static const CGFloat kBottomBarHeight = 44.0f;

@interface SnackbarOverlayViewExample ()
@property(nonatomic, assign) CGFloat floatingButtonOffset;
@end

@implementation SnackbarOverlayViewExample {
  BOOL _legacyMode;
}

- (void)viewDidLoad {
  [super viewDidLoad];
  [self setupExampleViews:@[ @"Show Snackbar", @"Toggle bottom bar" ]];
  self.title = @"Snackbar Overlay View";

  _legacyMode = YES;
  self.navigationItem.rightBarButtonItem =
  [[UIBarButtonItem alloc] initWithTitle:@"Legacy"
                                   style:UIBarButtonItemStylePlain
                                  target:self
                                  action:@selector(toggleModes)];

  self.floatingButton = [[MDCFloatingButton alloc] init];
  [self.floatingButton sizeToFit];
  [self.view addSubview:self.floatingButton];

  // Position the FAB.
  CGRect fabFrame = self.floatingButton.frame;
  fabFrame.origin.x = CGRectGetMaxX(self.view.bounds) - CGRectGetWidth(fabFrame) - kFABSideOffset;
  fabFrame.origin.y =
      CGRectGetMaxY(self.view.bounds) - CGRectGetHeight(fabFrame) - kFABBottomOffset;
  [self.floatingButton setBackgroundColor:[UIColor colorWithRed:11 / 255.0f
                                                          green:232 / 255.0f
                                                           blue:94 / 255.0f
                                                          alpha:1]
                                 forState:UIControlStateNormal];
  self.floatingButton.frame = fabFrame;
  self.floatingButton.autoresizingMask =
      (UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleTopMargin);
  [self.floatingButton addTarget:self
                          action:@selector(didTapFAB:)
                forControlEvents:UIControlEventTouchUpInside];

  self.bottomBar =
      [[UIView alloc] initWithFrame:CGRectMake(0, CGRectGetHeight(self.view.bounds),
                                               CGRectGetWidth(self.view.bounds), kBottomBarHeight)];
  self.bottomBar.autoresizingMask =
      UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleTopMargin;
  self.bottomBar.backgroundColor = [UIColor redColor];
  [self.view addSubview:self.bottomBar];

  // Make sure we're listening for overlay notifications.
  MDCOverlayObserver *manager = [MDCOverlayObserver observerForScreen:nil];
  [manager addTarget:self action:@selector(handleOverlayTransition:)];
}

- (void)viewWillDisappear:(BOOL)animated {
  [super viewWillDisappear:animated];

  [MDCSnackbarManager setBottomOffset:0];
}

- (void)toggleModes {
  _legacyMode = !_legacyMode;
  if (_legacyMode) {
    [self.navigationItem.rightBarButtonItem setTitle:@"Legacy"];
  } else {
    [self.navigationItem.rightBarButtonItem setTitle:@"New"];
  }
  MDCSnackbarMessage.usesLegacySnackbar = _legacyMode;
}

#pragma mark - Event Handling

- (void)collectionView:(UICollectionView *)collectionView
    didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
  [super collectionView:collectionView didSelectItemAtIndexPath:indexPath];
  if (indexPath.row == 0) {
    [self showSnackbar];
  } else {
    [self toggleBottomBar];
  }
  return;
}

- (void)showSnackbar {
  NSString *text = @"Snackbar Message";
  MDCSnackbarMessage *message = [MDCSnackbarMessage messageWithText:text];
  message.duration = 5.0f;
  [MDCSnackbarManager showMessage:message];
}

- (void)toggleBottomBar {
  self.isShowingBottomBar = !self.isShowingBottomBar;

  CGFloat bottomOffset = 0;
  CGFloat translation = kBottomBarHeight;

  if (self.isShowingBottomBar) {
    translation = -translation;
    bottomOffset = kBottomBarHeight;
  }

  [UIView animateWithDuration:0.25
                   animations:^{
                     self.bottomBar.center = CGPointMake(self.bottomBar.center.x,
                                                         self.bottomBar.center.y + translation);
                     [MDCSnackbarManager setBottomOffset:bottomOffset];
                   }];
}

- (void)didTapFAB:(id)sender {
  [self.floatingButton collapse:YES
                     completion:^{
                       [self.floatingButton expand:YES completion:nil];
                     }];
}

#pragma mark - Overlay Transitions

- (void)handleOverlayTransition:(id<MDCOverlayTransitioning>)transition {
  CGRect bounds = self.view.bounds;
  CGRect coveredRect = [transition compositeFrameInView:self.view];

  // Trim the covered rectangle to only consider the current view's bounds.
  CGRect boundedRect = CGRectIntersection(bounds, coveredRect);

  // How much should we shift the FAB up by.
  CGFloat fabVerticalShift = 0;
  CGFloat distanceFromBottom = 0;

  if (!CGRectIsEmpty(boundedRect)) {
    // Calculate how far from the bottom of the current view the overlay goes. All we really care
    // about is the absolute top of all overlays, we'll put the FAB above that point.
    distanceFromBottom = CGRectGetMaxY(bounds) - CGRectGetMinY(boundedRect);
  }

  // We're applying a transform to the FAB, so no need to account for padding or such.
  fabVerticalShift = self.floatingButtonOffset - distanceFromBottom;
  self.floatingButtonOffset = distanceFromBottom;

  [transition animateAlongsideTransition:^{
    self.floatingButton.center =
        CGPointMake(self.floatingButton.center.x, self.floatingButton.center.y + fabVerticalShift);
  }];
}

@end