components/FlexibleHeader/examples/FlexibleHeaderPageControlExample.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 "MaterialButtons.h"
#import "MaterialFlexibleHeader.h"
#import "MaterialPageControl.h"

static const CGFloat kFlexibleHeaderMinHeight = 200;

@interface FlexibleHeaderPageControlExample : UIViewController <UIScrollViewDelegate>

@property(nonatomic, strong) UIScrollView *scrollView;
@property(nonatomic, strong) MDCFlexibleHeaderViewController *fhvc;
@property(nonatomic, strong) MDCPageControl *pageControl;
@property(nonatomic, copy) NSArray *pages;
@property(nonatomic, strong) UIScrollView *pageScrollView;

@end

@implementation FlexibleHeaderPageControlExample

- (instancetype)init {
  self = [super init];
  if (self) {
    [self commonMDCFlexibleHeaderViewControllerInit];
  }
  return self;
}

- (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
  self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
  if (self) {
    [self commonMDCFlexibleHeaderViewControllerInit];
  }
  return self;
}

- (instancetype)initWithCoder:(NSCoder *)aDecoder {
  self = [super initWithCoder:aDecoder];
  if (self) {
    [self commonMDCFlexibleHeaderViewControllerInit];
  }
  return self;
}

- (void)commonMDCFlexibleHeaderViewControllerInit {
  _fhvc = [[MDCFlexibleHeaderViewController alloc] initWithNibName:nil bundle:nil];

  // Behavioral flags.
  _fhvc.topLayoutGuideAdjustmentEnabled = YES;
  _fhvc.inferTopSafeAreaInsetFromViewController = YES;
  _fhvc.headerView.minMaxHeightIncludesSafeArea = NO;

  _fhvc.headerView.maximumHeight = kFlexibleHeaderMinHeight;
  [self addChildViewController:_fhvc];
}

- (void)viewDidLoad {
  [super viewDidLoad];

  self.scrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];
  self.scrollView.backgroundColor = [UIColor whiteColor];
  self.scrollView.autoresizingMask =
      UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
  [self.view addSubview:self.scrollView];

  self.scrollView.delegate = self;
  self.fhvc.headerView.trackingScrollView = self.scrollView;

  self.fhvc.view.frame = self.view.bounds;
  [self.view addSubview:self.fhvc.view];
  [self.fhvc didMoveToParentViewController:self];

  self.fhvc.headerView.backgroundColor = [UIColor colorWithWhite:(CGFloat)0.1 alpha:1];

  CGFloat boundsWidth = CGRectGetWidth(self.fhvc.headerView.bounds);
  CGFloat boundsHeight = CGRectGetHeight(self.fhvc.headerView.bounds);

  NSArray *pageColors = @[
    [UIColor colorWithWhite:(CGFloat)0.1 alpha:1], [UIColor colorWithWhite:(CGFloat)0.2 alpha:1],
    [UIColor colorWithWhite:(CGFloat)0.3 alpha:1]
  ];

  // Scroll view configuration
  CGRect pageScrollViewFrame = CGRectMake(0, 0, boundsWidth, boundsHeight);
  self.pageScrollView = [[UIScrollView alloc] initWithFrame:pageScrollViewFrame];
  self.pageScrollView.autoresizingMask =
      UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
  self.pageScrollView.delegate = self;
  self.pageScrollView.pagingEnabled = YES;
  self.pageScrollView.contentSize = CGSizeMake(boundsWidth * pageColors.count, boundsHeight);
  self.pageScrollView.showsHorizontalScrollIndicator = NO;
  [self.fhvc.headerView addSubview:self.pageScrollView];

  NSMutableArray *pages = [NSMutableArray array];

  // Add pages to scrollView.
  for (NSUInteger i = 0; i < pageColors.count; i++) {
    CGRect pageFrame = CGRectOffset(pageScrollViewFrame, i * boundsWidth, 0);
    UILabel *page = [[UILabel alloc] initWithFrame:pageFrame];
    page.text = [NSString stringWithFormat:@"Page %lu", (unsigned long)(i + 1)];
    page.font = [UIFont systemFontOfSize:18];
    page.textColor = [UIColor colorWithWhite:1 alpha:(CGFloat)0.8];
    page.textAlignment = NSTextAlignmentCenter;
    page.backgroundColor = pageColors[i];
    page.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
    [self.pageScrollView addSubview:page];
    [pages addObject:page];
  }
  self.pages = [pages copy];

  // Page control configuration.
  self.pageControl = [[MDCPageControl alloc] init];
  self.pageControl.numberOfPages = pageColors.count;

  // We want the page control to span the bottom of the screen.
  CGSize pageControlSize = [self.pageControl sizeThatFits:self.view.bounds.size];
  self.pageControl.frame =
      CGRectMake(0, boundsHeight - pageControlSize.height, boundsWidth, pageControlSize.height);
  [self.pageControl addTarget:self
                       action:@selector(didChangePage:)
             forControlEvents:UIControlEventValueChanged];
  self.pageControl.autoresizingMask =
      UIViewAutoresizingFlexibleTopMargin | UIViewAutoresizingFlexibleWidth;
  [self.fhvc.headerView addSubview:self.pageControl];
}

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

  [self.navigationController setNavigationBarHidden:YES animated:animated];
}

// This method must be implemented for MDCFlexibleHeaderViewController's
// MDCFlexibleHeaderView to properly support MDCFlexibleHeaderShiftBehavior should you choose
// to customize it.
- (UIViewController *)childViewControllerForStatusBarHidden {
  return self.fhvc;
}

#pragma mark - <UIScrollViewDelegate>

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
  if (scrollView == self.scrollView) {
    [self.fhvc scrollViewDidScroll:scrollView];
  } else if (scrollView == self.pageScrollView) {
    [_pageControl scrollViewDidScroll:scrollView];
  }
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
  if (scrollView == self.pageScrollView) {
    [_pageControl scrollViewDidEndDecelerating:scrollView];
  }
}

- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView {
  if (scrollView == self.pageScrollView) {
    [_pageControl scrollViewDidEndScrollingAnimation:scrollView];
  }
}

#pragma mark - User events

- (void)didChangePage:(MDCPageControl *)sender {
  CGPoint offset = self.pageScrollView.contentOffset;
  offset.x = sender.currentPage * self.pageScrollView.bounds.size.width;
  [self.pageScrollView setContentOffset:offset animated:YES];
}

#pragma mark - Supplemental

- (UIStatusBarStyle)preferredStatusBarStyle {
  return UIStatusBarStyleLightContent;
}

- (void)viewDidLayoutSubviews {
  [super viewDidLayoutSubviews];

  self.scrollView.contentSize = self.view.bounds.size;
}

@end

@implementation FlexibleHeaderPageControlExample (CatalogByConvention)

+ (NSDictionary *)catalogMetadata {
  return @{
    @"breadcrumbs" : @[ @"Flexible Header", @"Page Control in Flexible Header" ],
    @"primaryDemo" : @NO,
    @"presentable" : @NO,
  };
}

- (BOOL)catalogShouldHideNavigation {
  return YES;
}

@end