iOS开发 剖析网易新闻标签栏视图切换(addChildViewController属性介绍)
本来只是打算介绍一下addChildViewController这个方法的,正好今天朋友去换工作面试问到网易新闻标签栏效果的实现,就结合它,用个小Demo实例介绍一下:(具体解释都写在了Demo里面的注释)
//// 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;