ios5中UIViewController新使用方法 ( 添加多個子ViewController )

在iOS5中，ViewController中新添加了下面幾個方法：

addChildViewController;

removeFromParentViewController;

transitionFromViewController:toViewController:duration:options:animations:completion;

willMoveToParentViewController;

didMoveToParentViewController;

下面詳細介紹一下addChildViewController，一個ViewController可以添加多個子ViewController，但是這些子ViewController只有一個是顯示到父視圖中的，可以通過transitionFromViewController:toViewController:duration:options:animations:completion:這個方法轉換顯示的子視圖。同時加入相應的動畫。下面以一個例子來說明，最後實現的效果：

點擊其中的按鈕如下：

下面詳細介紹一下上述效果的實現：

1. 創建項目，changeViewController。
2. 添加相應的viewController，MainViewController、FirstViewController、SecondViewController、ThirdViewController。如下圖：

3.把MainViewController添加到window中。

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.
    MainViewController *mainViewController=[[MainViewController alloc] initWithNibName:@"MainViewController" bundle:nil];
    self.window.rootViewController=mainViewController;
    [self.window makeKeyAndVisible];
    return YES;
}

4.在MainViewController中添加三個按鈕，並且連接onClickbutton方法。

5.在MainViewController中添加三個子controller

#pragma mark – View lifecycle - (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.

    FirstViewController *firstViewController=[[FirstViewController alloc] initWithNibName:@"FirstViewController" bundle:nil];
    [self addChildViewController:firstViewController];

    SecondViewController *secondViewController=[[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];
    [self addChildViewController:secondViewController];


    ThirdViewController *thirdViewController=[[ThirdViewController alloc] initWithNibName:@"ThirdViewController" bundle:nil];
    [self addChildViewController:thirdViewController];

    [contentView addSubview:thirdViewController.view];
    currentViewController=thirdViewController;
}

其中要把其中的一個子controller的view添加到根視圖中，這樣才能顯示出相應的視圖。

一定要先addChildViewController後才addSubview，否則會出現問題的。

6.點擊按鈕，切換視圖。

-(IBAction)onClickbutton:(id)sender
{
    FirstViewController *firstViewController=[self.childViewControllers objectAtIndex:0];
    ThirdViewController *thirdViewController=[self.childViewControllers objectAtIndex:2];
    SecondViewController *secondViewController=[self.childViewControllers objectAtIndex:1];
    if ((currentViewController==firstViewController&&[sender tag]==1)||(currentViewController==secondViewController&&[sender tag]==2) ||(currentViewController==thirdViewController&&[sender tag]==3) ) {
        return;
    }
    UIViewController *oldViewController=currentViewController;
    switch ([sender tag]) {
        case 1:
        {
            NSLog(@"留言及回覆");
            [self transitionFromViewController:currentViewController toViewController:firstViewController duration:4 options:UIViewAnimationOptionTransitionFlipFromLeft animations:^{
            }  completion:^(BOOL finished) {
                if (finished) {
                    currentViewController=firstViewController;
                }else{
                    currentViewController=oldViewController;
                }
            }];
}
            break;
        case 2:
        {
            NSLog(@"生日提醒");
            [self transitionFromViewController:currentViewController toViewController:secondViewController duration:1 options:UIViewAnimationOptionTransitionFlipFromTop animations:^{

            }  completion:^(BOOL finished) {
                if (finished) {
                  currentViewController=secondViewController;
                }else{
                    currentViewController=oldViewController;
                }
            }];
        }
            break;
        case 3:
        {
            NSLog(@"好友申請");
            [self transitionFromViewController:currentViewController toViewController:thirdViewController duration:1 options:UIViewAnimationOptionTransitionFlipFromBottom animations:^{

            }  completion:^(BOOL finished) {
                if (finished) {
                     currentViewController=thirdViewController;
                }else{
                    currentViewController=oldViewController;
                }
            }];
        }
            break;
        default:
            break;
    }
}

其中我把按鈕設置成不同的tag了。

這時候點擊按鈕，就可以切換子視圖了。

這樣寫的好處： 多個UIViewController之間切換可以添加動畫 當內存警告的時候，可以把當前不是激活狀態的ViewController內存釋放。