• iOS开发 剖析网易新闻标签栏视图切换(addChildViewController属性介绍)


                本来仅仅是打算介绍一下addChildViewController这种方法的,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:(详细解释都写在了Demo里面的凝视)

    //
    //  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 () <UIScrollViewDelegate>
    
    @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",@"財经",@"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,大家能够去看看
         */
        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添加了addChildViewController方法,而且希望我们在使用addSubview时,同一时候调用[self addChildViewController:child]方法将sub view相应的viewController也加到当前ViewController的管理中。
         对于那些当前临时不须要显示的subview,仅仅通过addChildViewController把subViewController加进去;须要显示时再调用transitionFromViewController方法。

    将其加入进入底层的ViewController中。 这样做的优点: 1.无疑,对页面中的逻辑更加分明了。相应的View相应相应的ViewController。

    2.当某个子View没有显示时,将不会被Load,降低了内存的使用。 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中新加入了以下几个方法: * 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,详细查看API) * animations 转换过程中得动画 * completion 转换完毕 */ [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; } }]; }



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  • 原文地址:https://www.cnblogs.com/mthoutai/p/7040531.html
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