material-components_material-components-ios/components/Tabs/examples/TabBarIconExample.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 "supplemental/TabBarIconExampleSupplemental.h"

#import "MaterialAppBar.h"
#import "MaterialColorScheme.h"
#import "MaterialTabs.h"
#import "MaterialTabs+ColorThemer.h"

@interface TabBarIconExample ()
@property(nonatomic, strong)UIBarButtonItem *addStarButtonItem;
@end

@implementation TabBarIconExample

- (id)init {
  self = [super init];
  if (self) {
    self.colorScheme = [[MDCSemanticColorScheme alloc] init];
    self.typographyScheme = [[MDCTypographyScheme alloc] init];
  }
  return self;
}

- (void)viewDidLoad {
  [super viewDidLoad];

  [self setupExampleViews];

  [self loadTabBar];

  self.addStarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Add"
                                                            style:UIBarButtonItemStylePlain
                                                           target:self
                                                           action:@selector(incrementDidTouch:)];
}

#pragma mark - Action

- (void)incrementDidTouch:(id)sender {
  [self incrementStarBadge];

  [self addStarCentered:NO];
}

- (void)incrementStarBadge {
  // Increment numeric badge value.
  UITabBarItem *starItem = self.tabBar.items[1];
  NSString *badgeValue = starItem.badgeValue;
  if (badgeValue) {
    NSInteger badgeNumber = badgeValue.integerValue;
    if (badgeNumber > 0) {
      // Update badge value directly - the cell should update immediately.
      starItem.badgeValue = [NSNumberFormatter localizedStringFromNumber:@(badgeNumber + 1)
                                                             numberStyle:NSNumberFormatterNoStyle];
    }
  }
}

#pragma mark - Private

- (void)loadTabBar {
  MDCTabBar *tabBar = [[MDCTabBar alloc] init];
  tabBar.delegate = self;
  tabBar.alignment = MDCTabBarAlignmentCenterSelected;

  NSBundle *bundle = [NSBundle bundleForClass:[TabBarIconExample class]];
  UIImage *infoImage =
      [UIImage imageNamed:@"TabBarDemo_ic_info" inBundle:bundle compatibleWithTraitCollection:nil];
  UIImage *starImage =
      [UIImage imageNamed:@"TabBarDemo_ic_star" inBundle:bundle compatibleWithTraitCollection:nil];
  tabBar.items = @[
    [[UITabBarItem alloc] initWithTitle:@"Info" image:infoImage tag:0],
    [[UITabBarItem alloc] initWithTitle:@"Stars" image:starImage tag:0]
  ];

  // Give the second item a badge
  [tabBar.items[1] setBadgeValue:@"1"];

  [MDCTabBarColorThemer applySemanticColorScheme:self.colorScheme toTabs:tabBar];

  tabBar.inkColor = [[UIColor whiteColor] colorWithAlphaComponent:0.1f];
  tabBar.itemAppearance = MDCTabBarItemAppearanceTitledImages;

  self.tabBar = tabBar;
  self.appBarViewController.headerStackView.bottomBar = self.tabBar;
  [self.appBarViewController.headerStackView setNeedsLayout];
}

- (void)changeAlignment:(id)sender {
  UIAlertController *sheet =
      [UIAlertController alertControllerWithTitle:nil
                                          message:nil
                                   preferredStyle:UIAlertControllerStyleActionSheet];
  sheet.popoverPresentationController.sourceView = self.alignmentButton;
  sheet.popoverPresentationController.sourceRect = self.alignmentButton.bounds;
  [sheet addAction:[UIAlertAction actionWithTitle:@"Leading"
                                            style:UIAlertActionStyleDefault
                                          handler:^(UIAlertAction *_Nonnull action) {
                                            [self setAlignment:MDCTabBarAlignmentLeading];
                                          }]];
  [sheet addAction:[UIAlertAction actionWithTitle:@"Center"
                                            style:UIAlertActionStyleDefault
                                          handler:^(UIAlertAction *_Nonnull action) {
                                            [self setAlignment:MDCTabBarAlignmentCenter];
                                          }]];
  [sheet addAction:[UIAlertAction actionWithTitle:@"Justified"
                                            style:UIAlertActionStyleDefault
                                          handler:^(UIAlertAction *_Nonnull action) {
                                            [self setAlignment:MDCTabBarAlignmentJustified];
                                          }]];
  [sheet addAction:[UIAlertAction actionWithTitle:@"Selected Center"
                                            style:UIAlertActionStyleDefault
                                          handler:^(UIAlertAction *_Nonnull action) {
                                            [self setAlignment:MDCTabBarAlignmentCenterSelected];
                                          }]];
  [self presentViewController:sheet animated:YES completion:nil];
}

- (void)setAlignment:(MDCTabBarAlignment)alignment {
  [self.tabBar setAlignment:alignment animated:YES];
}

#pragma mark - MDCTabBarDelegate

- (void)tabBar:(MDCTabBar *)tabBar didSelectItem:(UITabBarItem *)item {
  NSUInteger index = [tabBar.items indexOfObject:item];
  NSAssert(index != NSNotFound, @"The MDCTabBar does not contain the expected UITabBarItem.");

  [self.scrollView setContentOffset:CGPointMake(index * CGRectGetWidth(self.view.bounds), 0)
                           animated:YES];
  if (index == 0) {
    self.navigationItem.rightBarButtonItem = nil;
  } else {
    self.navigationItem.rightBarButtonItem = self.addStarButtonItem;
  }
}

@end