多视图应用

一、效果

1. 启动进入蓝色视图界面

2. 点击“按我”按钮跳出警告框

3. 点击最下按钮“Switch View”跳转到黄色视图

二、分析

1. 由三个控制器组成，一个根控制器，控制蓝色视图控制器与黄色视图控制器的转换

2. 最下方的工具栏始终位于视图的最顶层，才不至于被视图覆盖

3. 程序启动只需加载其一，所以用懒加载加载另一视图

三、 实现

1. 使用Main.Storyboard搭建布局

2. 创建蓝、黄控制器模型

3.SwichingViewController.m实现代码

//
//  ViewController.m
//  6.1-多视图应用
//
//  Created by LinKun on 16/7/15.
//  Copyright © 2016年 Apress. All rights reserved.
//
#pragma mark - 根控制器复制两个视图控制器的转换，所以应该包含它们
#import "SwitchingViewController.h"
#import "BlueViewController.h"
#import "YellowViewController.h"

@interface SwitchingViewController ()
// 两个子视图控制器
@property (strong, nonatomic) YellowViewController *yellowViewController;
@property (strong, nonatomic) BlueViewController *blueViewController;

@end

@implementation SwitchingViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    // 实例化storyboard中标记为“Blue”的视图控制器，及蓝色视图控制器的位置大小
    self.blueViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"Blue"];
    self.blueViewController.view.frame = self.view.frame;
    // 切换控制器
    [self switchViewFromViewController:nil toViewController:self.blueViewController];
    
}

#pragma mark - 按钮动作
- (IBAction)switchViews:(id)sender {
    // 懒加载：加载将要切换到的控制器
    if (!self.yellowViewController.view.superview) {
        if (!self.yellowViewController) {
            self.yellowViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"Yellow"];
        }
    }else {
            if (!self.blueViewController) {
                self.blueViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"Blue"];
            }
        }
    
    // 动画效果：开始动画，持续0.4s，运动曲线
    [UIView beginAnimations:@"View Flip" context:NULL];
    [UIView setAnimationDuration:0.4];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
    
    
    if (!self.yellowViewController.view.superview) {
        // 动画过渡
        [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight forView:self.view cache:YES];
        self.yellowViewController.view.frame = self.view.frame;
        [self switchViewFromViewController:self.blueViewController toViewController:self.yellowViewController];
    } else {
        [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:self.view cache:YES];
        self.blueViewController.view.frame = self.view.frame;
        [self switchViewFromViewController:self.yellowViewController toViewController:self.blueViewController];
    }
    [UIView commitAnimations];
}

#pragma mark - 转换控制器
- (void)switchViewFromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC {
   // 把当前控制器移除
    if (fromVC != nil) {
        [fromVC willMoveToParentViewController:nil];
        [fromVC.view removeFromSuperview];
        [fromVC removeFromParentViewController];
    }
    // 把转换的控制器加进来
    if (toVC != nil) {
        [self addChildViewController:toVC];
        [self.view insertSubview:toVC.view atIndex:0];
        [toVC didMoveToParentViewController:self];
    }
    
}

@end

备注：要切换控制器，先将要切换到的控制器加载出来，然后移除当前控制器，把另一控制器加载到根控制器

4. BlueViewController.h

//
//  BlueViewController.m
//  6.1-多视图应用
//
//  Created by LinKun on 16/7/15.
//  Copyright © 2016年 Apress. All rights reserved.
//

#import "BlueViewController.h"

@interface BlueViewController ()

@end

@implementation BlueViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
}

#pragma mark - 蓝色视图按钮动作
- (IBAction)blueButtonPressed:(id)sender {

    // 创建警告表单
    UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"Blue View Button Pressed" message:@"You pressed the button on the blue view" preferredStyle:UIAlertControllerStyleAlert];
    // 创建按钮
    UIAlertAction *action = [UIAlertAction actionWithTitle:@"Yes i did" style:UIAlertActionStyleDefault handler:nil];
    // 把按钮加到表单，把控制权交给表单
    [alert addAction:action];
    [self presentViewController:alert animated:YES completion:nil];
}

@end

5. YellowViewController.m

//
//  YellowViewController.m
//  6.1-多视图应用
//
//  Created by LinKun on 16/7/15.
//  Copyright © 2016年 Apress. All rights reserved.
//

#import "YellowViewController.h"

@interface YellowViewController ()

@end

@implementation YellowViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
}

#pragma mark - 黄色视图按钮动作
- (IBAction)yellowButtonPressed:(id)sender {
    // 创建警告表单
    UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"Yellow View Button Pressed" message:@"You pressed the yellow on the blue view" preferredStyle:UIAlertControllerStyleAlert];
    // 创建按钮
    UIAlertAction *action = [UIAlertAction actionWithTitle:@"Yes i did" style:UIAlertActionStyleDefault handler:nil];
    
    // 把按钮加到表单，把控制器权交给表单
    [alert addAction:action];
    [self presentViewController:alert animated:YES completion:nil];
}

@end