精通IOS开发第六版学习第六章---多页面应用

来源：互联网发布：sqlalchemy 原生sql 编辑：程序博客网时间：2024/05/20 06:39

涉及知识点

1. the root controller

它是一个当应用加载的时候用到的控制器。

这个root controller通常是UINavigationController和UITabBarController的实例或者是一个客户定制过的UIViewController的子类的实例。

2. content view

content view 是我们放置显示控件的地方。它有自己的controller。每个content view都是一个UIView或者是它的子类。

3. scene场景

在storyboard中，每个scene都有一个content view和它的controller

4. lazy loading

懒加载，在需要的时候在加载需要的内容。

小例子实现代码如下：

这个例子有点过于简单。而且依赖于storyboard。

#import "ViewController.h"#import "BlueViewController.h"#import "YellowViewController.h"@interface ViewController ()@property (nonatomic, strong) YellowViewController *yellowViewController;@property (nonatomic, strong) BlueViewController *blueViewController;@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view, typically from a nib.    self.blueViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"Blue"];    [self.view insertSubview:_blueViewController.view atIndex:0];}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.    if (!self.blueViewController.view.superview) {        self.blueViewController = nil;    }else{        self.yellowViewController = nil;    }}- (IBAction)switchViews:(id)sender{        [UIView beginAnimations:@"View Flip" context:NULL];    [UIView setAnimationDuration:0.4];    [UIView setAnimationCurve:UIViewAnimationCurveEaseOut];    if (!self.yellowViewController.view.superview) {        if (!self.yellowViewController) {            self.yellowViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"Yellow"];        }        [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight forView:self.view cache:YES];        [self.blueViewController.view removeFromSuperview];        [self.view insertSubview:self.yellowViewController.view atIndex:0];    }else{        if (!self.blueViewController) {            self.blueViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"Blue"];        }        [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:self.view cache:YES];        [self.yellowViewController.view removeFromSuperview];        [self.view insertSubview:self.blueViewController.view atIndex:0];    }    [UIView commitAnimations];    }

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