iOS仿网易新闻滚动导航条效果

// 头条ViewController, 其它控制器和这个控制器都一样，只是背景颜色不同而已#import <UIKit/UIKit.h>@interface TopLineViewController : UIViewController@end//----------------------------------------------------------------#import "TopLineViewController.h"@interface TopLineViewController ()@end@implementation TopLineViewController- (void)viewDidLoad {  [super viewDidLoad];  self.view.backgroundColor = [UIColor blackColor];}@end

#import <UIKit/UIKit.h>@interface ViewController : UIViewController@end//----------------------------------------------------------------#import "ViewController.h"#import "TopLineViewController.h"#import "TechnologyViewController.h"#import "CarViewController.h"#import "SportsViewController.h"#import "VideoViewController.h"#import "ImageViewController.h"#import "HotViewController.h"#define ScreenWidth [UIScreen mainScreen].bounds.size.width#define ScreenHeight [UIScreen mainScreen].bounds.size.height@interface ViewController () <UIScrollViewDelegate>@property (weak, nonatomic) IBOutlet UIScrollView *titleScrollView;@property (weak, nonatomic) IBOutlet UIScrollView *contentScrollView;@property (strong, nonatomic) NSMutableArray *buttons;@property (strong, nonatomic) UIButton *selectedButton;@end@implementation ViewController- (void)viewDidLoad {  [super viewDidLoad];  self.navigationItem.title = @"网易新闻";  // 1. 初始化标题滚动视图上的按钮  [self initButtonsForButtonScrollView];}- (void) initButtonsForButtonScrollView {  // 初始化子控制器  [self initChildViewControllers];  CGFloat buttonWidth = 100;  CGFloat buttonHeight = 40;  NSInteger childViewControllerCount = self.childViewControllers.count;  for (NSInteger i = 0; i < childViewControllerCount; i++) {    UIViewController *childViewController = self.childViewControllers[i];    UIButton *titleButton = [UIButton buttonWithType:UIButtonTypeCustom];    titleButton.tag = i;    CGFloat x = i * buttonWidth;    titleButton.frame = CGRectMake(x, 0, buttonWidth, buttonHeight);    [titleButton setTitle:childViewController.title forState:UIControlStateNormal];    [titleButton setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];    [titleButton addTarget:self action:@selector(titleButtonOnClick:) forControlEvents:UIControlEventTouchUpInside];    [self.titleScrollView addSubview:titleButton];    [self.buttons addObject:titleButton];  }  self.titleScrollView.contentSize = CGSizeMake(buttonWidth * childViewControllerCount, 0);  self.titleScrollView.showsHorizontalScrollIndicator = NO;  self.titleScrollView.bounces = NO;  self.contentScrollView.contentSize = CGSizeMake(ScreenWidth * childViewControllerCount, 0);  self.contentScrollView.showsHorizontalScrollIndicator = NO;  self.contentScrollView.pagingEnabled = YES;  self.contentScrollView.delegate = self;  // 禁止额外滚动区域  self.automaticallyAdjustsScrollViewInsets = NO;  // 初始化时默认选中第一个  [self titleButtonOnClick:self.buttons[0]];}- (void)titleButtonOnClick:(UIButton *)button {  // 1. 选中按钮  [self selectingButton:button];  // 2. 显示子视图  [self addViewToContentScrollView:button];}- (void)selectingButton:(UIButton *)button {  [_selectedButton setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];  _selectedButton.transform = CGAffineTransformMakeScale(1.0, 1.0);  [button setTitleColor:[UIColor redColor] forState:UIControlStateNormal];  button.transform = CGAffineTransformMakeScale(1.3, 1.3); // 选中字体变大，按钮变大，字体也跟着变大  _selectedButton = button;  // 选中按钮时要让选中的按钮居中  CGFloat offsetX = button.frame.origin.x - ScreenWidth * 0.5;  CGFloat maxOffsetX = self.titleScrollView.contentSize.width - ScreenWidth;  if (offsetX < 0) {    offsetX = 0;  } else if (offsetX > maxOffsetX) {    offsetX = maxOffsetX;  }  [self.titleScrollView setContentOffset:CGPointMake(offsetX, 0) animated:YES];}- (void)addViewToContentScrollView:(UIButton *)button {  NSInteger i = button.tag;  UIViewController *childViewController = self.childViewControllers[i];  CGFloat x = i * ScreenWidth;  // 防止添加多次  if (childViewController.view.subviews != nil) {    childViewController.view.frame = CGRectMake(x, 0, ScreenWidth, ScreenHeight);    [self.contentScrollView addSubview:childViewController.view];  }  self.contentScrollView.contentOffset = CGPointMake(x, 0);}#pragma mark - UIScrollViewDelegate- (void)scrollViewDidScroll:(UIScrollView *)scrollView {}// 滚动结束时，将对应的视图控制器的视图添加到内容滚动视图中- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {  NSInteger i = self.contentScrollView.contentOffset.x / ScreenWidth;  [self addViewToContentScrollView:_buttons[i]];  // 内容滚动视图结束后选中对应的标题按钮  [self selectingButton:_buttons[i]];}- (void)initChildViewControllers {  // 0.头条  TopLineViewController * topViewController = [[TopLineViewController alloc] init];  topViewController.title = @"头条";  [self addChildViewController:topViewController];  // 1.科技  TechnologyViewController * technologyViewController = [[TechnologyViewController alloc] init];  technologyViewController.title = @"科技";  [self addChildViewController:technologyViewController];  // 2.汽车  CarViewController * carViewController = [[CarViewController alloc] init];  carViewController.title = @"汽车";  [self addChildViewController:carViewController];  // 3.体育  SportsViewController * sportsViewController = [[SportsViewController alloc] init];  sportsViewController.title = @"体育";  [self addChildViewController:sportsViewController];  // 4.视频  VideoViewController * videoViewController = [[VideoViewController alloc] init];  videoViewController.title = @"视频";  [self addChildViewController:videoViewController];  // 5.图片  ImageViewController * imageViewController = [[ImageViewController alloc] init];  imageViewController.title = @"图片";  [self addChildViewController:imageViewController];  // 6.热点  HotViewController * hotViewController = [[HotViewController alloc] init];  hotViewController.title = @"热点";  [self addChildViewController:hotViewController];}- (NSMutableArray *)buttons {  if (_buttons == nil) {    _buttons = [NSMutableArray array];  }  return _buttons;}@end