////  HMTMainViewController.m//  UIScrollView////  Created by HMT on 14-6-25.//  Copyright (c) 2014年 humingtao. All rights reserved.//#import "HMTMainViewController.h"#import "HMTFirstViewController.h"#import "HMTSecondViewController.h"#import "HMTThirdViewController.h"@interface HMTMainViewController () 
    
     @property (nonatomic ,strong) HMTThirdViewController  *thirdVC;@property (nonatomic ,strong) HMTFirstViewController  *firstVC;@property (nonatomic ,strong) HMTSecondViewController *secondVC;@property (nonatomic ,strong) UIViewController *currentVC;@property (nonatomic ,strong) UIScrollView *headScrollView;  //  顶部滚动视图@property (nonatomic ,strong) NSArray *headArray;@end@implementation HMTMainViewController- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];    if (self) {        // Custom initialization    }    return self;}- (void)viewDidLoad{    [super viewDidLoad];    // Do any additional setup after loading the view.       self.navigationItem.title = @"网易新闻Demo";        self.headArray = @[@"头条",@"娱乐",@"体育",@"财经",@"科技",@"NBA",@"手机"];    /**     *   automaticallyAdjustsScrollViewInsets   又被这个属性坑了     *   我"UI高级"里面一篇文章着重讲了它,大家可以去看看     */    self.automaticallyAdjustsScrollViewInsets = NO;    self.headScrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 64, 320, 40)];    self.headScrollView.backgroundColor = [UIColor purpleColor];    self.headScrollView.contentSize = CGSizeMake(560, 0);    self.headScrollView.bounces = NO;    self.headScrollView.pagingEnabled = YES;    [self.view addSubview:self.headScrollView];    for (int i = 0; i < [self.headArray count]; i++) {                UIButton *button = [UIButton buttonWithType:UIButtonTypeSystem];        button.frame = CGRectMake(0 + i*80, 0, 80, 40);        [button setTitle:[self.headArray objectAtIndex:i] forState:UIControlStateNormal];        button.tag = i + 100;        [button addTarget:self action:@selector(didClickHeadButtonAction:) forControlEvents:UIControlEventTouchUpInside];        [self.headScrollView addSubview:button];            }        /*     苹果新的API增加了addChildViewController方法，并且希望我们在使用addSubview时，同时调用[self addChildViewController:child]方法将sub view对应的viewController也加到当前ViewController的管理中。     对于那些当前暂时不需要显示的subview，只通过addChildViewController把subViewController加进去；需要显示时再调用transitionFromViewController方法。将其添加进入底层的ViewController中。     这样做的好处：          1.无疑，对页面中的逻辑更加分明了。相应的View对应相应的ViewController。     2.当某个子View没有显示时，将不会被Load，减少了内存的使用。     3.当内存紧张时，没有Load的View将被首先释放，优化了程序的内存释放机制。     */        /**     *  在iOS5中，ViewController中新添加了下面几个方法：     *  addChildViewController:     *  removeFromParentViewController     *  transitionFromViewController:toViewController:duration:options:animations:completion:     *  willMoveToParentViewController:     *  didMoveToParentViewController:     */    self.firstVC = [[HMTFirstViewController alloc] init];    [self.firstVC.view setFrame:CGRectMake(0, 104, 320, 464)];    [self addChildViewController:_firstVC];        self.secondVC = [[HMTSecondViewController alloc] init];    [self.secondVC.view setFrame:CGRectMake(0, 104, 320, 464)];        self.thirdVC = [[HMTThirdViewController alloc] init];    [self.thirdVC.view setFrame:CGRectMake(0, 104, 320, 464)];        //  默认,第一个视图(你会发现,全程就这一个用了addSubview)    [self.view addSubview:self.firstVC.view];    self.currentVC = self.firstVC;    }- (void)didClickHeadButtonAction:(UIButton *)button{    //  点击处于当前页面的按钮,直接跳出    if ((self.currentVC == self.firstVC && button.tag == 100)||(self.currentVC == self.secondVC && button.tag == 101.)) {        return;    }else{            //  展示2个,其余一样,自行补全噢        switch (button.tag) {            case 100:                [self replaceController:self.currentVC newController:self.firstVC];                break;            case 101:                [self replaceController:self.currentVC newController:self.secondVC];                break;            case 102:                //.......                break;            case 103:                //.......                break;            case 104:                //.......                break;            case 105:                //.......                break;            case 106:                //.......                break;                //.......            default:                break;        }    }}//  切换各个标签内容- (void)replaceController:(UIViewController *)oldController newController:(UIViewController *)newController{    /**     *            着重介绍一下它     *  transitionFromViewController:toViewController:duration:options:animations:completion:     *  fromViewController      当前显示在父视图控制器中的子视图控制器     *  toViewController        将要显示的姿势图控制器     *  duration                动画时间(这个属性,old friend 了 O(∩_∩)O)     *  options                 动画效果(渐变,从下往上等等,具体查看API)     *  animations              转换过程中得动画     *  completion              转换完成     */        [self addChildViewController:newController];    [self transitionFromViewController:oldController toViewController:newController duration:2.0 options:UIViewAnimationOptionTransitionCrossDissolve animations:nil completion:^(BOOL finished) {                        if (finished) {                                [newController didMoveToParentViewController:self];            [oldController willMoveToParentViewController:nil];            [oldController removeFromParentViewController];            self.currentVC = newController;                        }else{                                self.currentVC = oldController;                        }    }];}