ChildViewController的应用

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• ChildViewController的应用

  viewControlle中可以添加多个subView，在需要的时候显示出来；另一种方法是通过向parentViewController中可以添加多个childCiewController;来控制页面中的subView，降低代码耦合度；通过切换子视图控制器，可以显示不同的view；，替代之前的addSubView的管理。

  本节通过类似百度新闻模块切换的界面来演示ChileViewController的应用：

  文档结构：

  
  

  代码演示：

  view source print ?

  001. #import "MainViewController.h"

  002. #import "FirstViewController.h"

  003. #import "SecondViewController.h"

  004. #import "ThirdViewController.h"

  005. @interface MainViewController ()

  006. @property (nonatomic, strong) FirstViewController *firstVC;

  007. @property (nonatomic, strong) SecondViewController *secondVC;

  008. @property (nonatomic, strong) ThirdViewController *thirdVC;

  009. @property (nonatomic, strong) UIViewController *currentVC;

  010.  

  011. @property (nonatomic, strong) UIScrollView *headScrollView;

  012. @property (nonatomic, strong) NSMutableArray *itemArray;

  013. @property (nonatomic, strong) UIView *contentView;

  014. @end

  015.  

  016. @implementation MainViewController

  017. - (void)loadView{

  018. [super loadView];

  019. [self initialization];

  020. }

  021.  

  022. - (void)viewDidLoad {

  023. [super viewDidLoad];

  024. [self loadBaseUI];

  025. }

  026.  

  027. - (void)initialization{

  028. _itemArray = [NSMutableArray arrayWithObjects:@"头条",@"今日",@"焦点", nil];

  029. }

  030.  

  031. - (void)loadBaseUI{

  032. self.title = @"首页";

  033. _headScrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, 44)];

  034. _headScrollView.backgroundColor = [UIColor colorWithWhite:0.902 alpha:1.000];

  035. for (int i = 0; i<_itemArray.count; i++) {

  036. UIButton *itemButton = [[UIButton alloc]initWithFrame:CGRectMake(i*([UIScreen mainScreen].bounds.size.width/_itemArray.count), 0, [UIScreen mainScreen].bounds.size.width/_itemArray.count, 44)];

  037. itemButton.tag = 100+i;

  038. itemButton.backgroundColor = [UIColor clearColor];

  039. NSDictionary *dic = @{NSForegroundColorAttributeName:[UIColor purpleColor],NSFontAttributeName:[UIFont systemFontOfSize:14.0f]};

  040. [itemButton setAttributedTitle:[[NSAttributedString alloc]initWithString:_itemArray[i] attributes:dic] forState:UIControlStateNormal];

  041. [itemButton addTarget:self action:@selector(buttonClick:) forControlEvents:UIControlEventTouchUpInside];

  042. [_headScrollView addSubview:itemButton];

  043. }

  044. [_headScrollView setContentSize:CGSizeMake([UIScreen mainScreen].bounds.size.width, 44)];

  045. _headScrollView.showsHorizontalScrollIndicator = NO;

  046. _headScrollView.showsVerticalScrollIndicator = NO;

  047. [self.view addSubview:_headScrollView];

  048.  

  049. _contentView = [[UIView alloc]initWithFrame:CGRectMake(0, 44, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height - 44 - 64)];

  050. _contentView.backgroundColor = [UIColor clearColor];

  051. [self.view addSubview:_contentView];

  052.  

  053. [self addSubControllers];

  054. }

  055.  

  056. #pragma mark - privatemethods

  057. - (void)addSubControllers{

  058. _firstVC = [[FirstViewController alloc]initWithNibName:@"FirstViewController" bundle:nil];

  059. [self addChildViewController:_firstVC];

  060.  

  061. _secondVC = [[SecondViewController alloc]initWithNibName:@"SecondViewController" bundle:nil];

  062. [self addChildViewController:_secondVC];

  063.  

  064. _thirdVC = [[ThirdViewController alloc]initWithNibName:@"ThirdViewController" bundle:nil];

  065. [self addChildViewController:_thirdVC];

  066.  

  067. //调整子视图控制器的Frame已适应容器View

  068. [self fitFrameForChildViewController:_firstVC];

  069. //设置默认显示在容器View的内容

  070. [self.contentView addSubview:_firstVC.view];

  071.  

  072. NSLog(@"%@",NSStringFromCGRect(self.contentView.frame));

  073. NSLog(@"%@",NSStringFromCGRect(_firstVC.view.frame));

  074.  

  075. _currentVC = _firstVC;

  076. }

  077.  

  078. - (void)buttonClick:(UIButton *)sender{

  079. if ((sender.tag == 100 && _currentVC == _firstVC) || (sender.tag == 101 && _currentVC == _secondVC) || (sender.tag == 102 && _currentVC == _thirdVC)) {

  080. return;

  081. }

  082. switch (sender.tag) {

  083. case 100:{

  084. [self fitFrameForChildViewController:_firstVC];

  085. [self transitionFromOldViewController:_currentVC toNewViewController:_firstVC];

  086. }

  087. break;

  088. case 101:{

  089. [self fitFrameForChildViewController:_secondVC];

  090. [self transitionFromOldViewController:_currentVC toNewViewController:_secondVC];

  091. }

  092. break;

  093. case 102:{

  094. [self fitFrameForChildViewController:_thirdVC];

  095. [self transitionFromOldViewController:_currentVC toNewViewController:_thirdVC];

  096. }

  097. break;

  098. }

  099. }

  100.  

  101. - (void)fitFrameForChildViewController:(UIViewController *)chileViewController{

  102. CGRect frame = self.contentView.frame;

  103. frame.origin.y = 0;

  104. chileViewController.view.frame = frame;

  105. }

  106.  

  107. //转换子视图控制器

  108. - (void)transitionFromOldViewController:(UIViewController *)oldViewControllertoNewViewController:(UIViewController *)newViewController{

  109. [self transitionFromViewController:oldViewController toViewController:newViewController duration:0.3options:UIViewAnimationOptionTransitionCrossDissolve animations:nil completion:^(BOOL finished) {

  110. if (finished) {

  111. [newViewController didMoveToParentViewController:self];

  112. _currentVC = newViewController;

  113. }else{

  114. _currentVC = oldViewController;

  115. }

  116. }];

  117. }

  118.  

  119. //移除所有子视图控制器

  120. - (void)removeAllChildViewControllers{

  121. for (UIViewController *vc in self.childViewControllers) {

  122. [vc willMoveToParentViewController:nil];

  123. [vc removeFromParentViewController];

  124. }

  125. }

  126.  

  127. /**

  128. *  方法说明：

  129. *  1、addChildViewController:向父VC中添加子VC，添加之后自动调用willMoveToParentViewController:父VC

  130. *  2、removeFromParentViewController:将子VC从父VC中移除，移除之后自动调用

  131. didMoveToParentViewController:nil

  132. *  3、willMoveToParentViewController:  当向父VC添加子VC之后，该方法会自动调用。若要从父VC移除子VC，需要在移除之前调用该方法，传入参数nil。

  133. *  4、didMoveToParentViewController:  当向父VC添加子VC之后，该方法不会被自动调用，需要显示调用告诉编译器已经完成添加（事实上不调用该方法也不会有问题，不太明白）; 从父VC移除子VC之后，该方法会自动调用，传入的参数为nil,所以不需要显示调用。

  134. */

  135.  

  136. /**

  137. *  注意点：

  138. 要想切换子视图控制器a/b,a/b必须均已添加到父视图控制器中，不然会报错

  139. */

  140. @end

  最终效果：(实现了3个视图之间的切换)

    

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