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

转自 http://blog.csdn.net/hmt20130412/article/details/34523235?utm_source=tuicool 还有好多知识 大家可以学习

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)

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//

// 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",@"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;

}

}];

}