试图切换能够用transitionFromViewController。
步骤：
View Controller中能够加入多个sub view，在须要的时候显示出来；
能够通过viewController(parent)中能够加入多个child viewController;来控制页面中的sub view。减少代码耦合度；
通过切换，能够显示不同的view；，替代之前的addSubView的管理
代码：
苹果API中所带方法：
addChildViewController:
removeFromParentViewController
transitionFromViewController:toViewController:duration:options:animations:completion:
willMoveToParentViewController:
didMoveToParentViewController:
以下具体介绍一下addChildViewController，一个ViewController能够加入多个子ViewController，可是这些子ViewControlle要想显示出来，须要把子controller的视图加入到父视图的对应位置r，能够通过transitionFromViewController:toViewController:duration:options:animations:completion:这种方法转换显示的子视图。
同一时候加入对应的动画。
以下以一个样例来说明这几个新方法：
以下具体介绍一下上述效果的实现：
- 创建项目，changeViewController。
- 加入对应的viewController，MainViewController、FirstViewController、SecondViewController、ThirdViewController。
3.把MainViewController加入到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中加入三个按钮。而且连接onClickbutton方法。
5.在MainViewController中加入三个子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;
}
当中要把当中的一个子controller的view加入到根视图中，这样才干显示出对应的视图。
6.点击button，切换视图。
-(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:
{
[self transitionFromViewController:currentViewController toViewController:firstViewController duration:4 options:UIViewAnimationOptionTransitionFlipFromLeft animations:^{
} completion:^(BOOL finished) {
if (finished) {
currentViewController=firstViewController;
}else{
currentViewController=oldViewController;
}
}];
}
break;
case 2:
{
[self transitionFromViewController:currentViewController toViewController:secondViewController duration:1 options:UIViewAnimationOptionTransitionFlipFromTop animations:^{
} completion:^(BOOL finished) {
if (finished) {
currentViewController=secondViewController;
}else{
currentViewController=oldViewController;
}
}];
}
break;
case 3:
{
NSLog(@"好友申请");
[self transitionFromViewController:currentViewController toViewController:thirdViewController duration:1 options:UIViewAnimationOptionTransitionFlipFromBottom animations:^{
} completion:^(BOOL finished) {
if (finished) {
currentViewController=thirdViewController;
}else{
currentViewController=oldViewController;
}
}];
}
break;
default:
break;
}
}
当中我把button设置成不同的tag了。
这时候点击button，就能够切换子视图了。
能够看到，这些view在没有使用时。是不会被load的，而且当有Memory Warning时。当前没有显示的view自己主动被unload掉了。
这样写的优点：
- 多个UIViewController之间切换能够加入动画
- 当内存警告的时候。能够把当前不是激活状态的ViewController内存释放。所以新的方法确实能有效地节省内存，也能方便地处理内存不足时的资源回收
- 能够把代码更好分开