iOS7中的ViewController切换

实现控制器之间的切换:(实现弹跳的效果:)

先实现一个自定义的类似的modal present的效果，与普通效果不同的是，我们希望modalVC出现的时候不要那么乏味的就简单从底部出现，而是带有一个弹性效果:

 

ViewController的实现:

 

//
//  ViewController.m
//  ViewController切换
//
//  Created by 思 彭 on 16/3/29.
//  Copyright © 2016年 combanc. All rights reserved.
//

#import "ViewController.h"
#import "ModalViewController.h"
#import "BouncePresentAnimation.h"



@interface ViewController ()<ModalViewControllerDelegate,UIViewControllerTransitioningDelegate>

@property (nonatomic, strong) BouncePresentAnimation *presentAnimation;


@end

@implementation ViewController


- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        
        _presentAnimation = [BouncePresentAnimation new];
        
    }
    return self;
}



- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor lightGrayColor];
    
    UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    button.frame = CGRectMake(80.0, 210.0, 160.0, 40.0);
    button.backgroundColor = [UIColor redColor];
    [button setTitle:@"Dismiss me" forState:UIControlStateNormal];
    [button addTarget:self action:@selector(buttonClicked:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];
    
    
}


// 按钮点击触发方法

-(void) buttonClicked:(id)sender
{
    ModalViewController *mvc = [[ModalViewController alloc] init];
    
    mvc.delegate = self;
    mvc.transitioningDelegate = self;
    
    //模态到ModalViewController
    [self presentViewController:mvc animated:YES completion:nil];
}


//实现协议方法

-(void)modalViewControllerDidClickedDismissButton:(ModalViewController *)viewController
{
    [self dismissViewControllerAnimated:YES completion:nil];
}



- (id <UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source
{
    return self.presentAnimation;
}




- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

ModalViewController的实现:

#import <UIKit/UIKit.h>

@class ModalViewController;

@protocol  ModalViewControllerDelegate<NSObject>


-(void) modalViewControllerDidClickedDismissButton:(ModalViewController *)viewController;


@end


@interface ModalViewController : UIViewController

@property (nonatomic, weak) id<ModalViewControllerDelegate> delegate;

@end

//
//  ModalViewController.m
//  ViewController切换
//
//  Created by 思 彭 on 16/3/29.
//  Copyright © 2016年 combanc. All rights reserved.
//

#import "ModalViewController.h"

@implementation ModalViewController


- (void)viewDidLoad{

    [super viewDidLoad];
    
    // Do any additional setup after loading the view.
    self.view.backgroundColor = [UIColor grayColor];
    
    UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    button.frame = CGRectMake(80.0, 210.0, 160.0, 40.0);
    button.backgroundColor = [UIColor greenColor];
    [button setTitle:@"Dismiss me" forState:UIControlStateNormal];
    [button addTarget:self action:@selector(buttonClicked:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];
    
}

// 按钮点击触发方法

-(void) buttonClicked:(id)sender
{
    if (self.delegate && [self.delegate respondsToSelector:@selector(modalViewControllerDidClickedDismissButton:)]) {
        [self.delegate modalViewControllerDidClickedDismissButton:self];
    }
}

    

@end

BouncePresentAnimation的代码实现:

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>


// 在遵守协议UIViewControllerAnimatedTransitioning记得导入UIKit框架

@interface BouncePresentAnimation : NSObject<UIViewControllerAnimatedTransitioning>


@end

//
//  BouncePresentAnimation.m
//  ViewController切换
//
//  Created by 思 彭 on 16/3/29.
//  Copyright © 2016年 combanc. All rights reserved.
//

#import "BouncePresentAnimation.h"

@implementation BouncePresentAnimation



#pragma mark - UIViewControllerAnimatedTransitioning代理

- (NSTimeInterval)transitionDuration:(nullable id <UIViewControllerContextTransitioning>)transitionContext{
    
    return .6f;
    
    
}


- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext{
    
    // 1. Get controllers from transition context
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    
    // 2. Set init frame for toVC
    CGRect screenBounds = [[UIScreen mainScreen] bounds];
    CGRect finalFrame = [transitionContext finalFrameForViewController:toVC];
    toVC.view.frame = CGRectOffset(finalFrame, 0, screenBounds.size.height);
    
    // 3. Add toVC's view to containerView
    UIView *containerView = [transitionContext containerView];
    [containerView addSubview:toVC.view];
    
    // 4. Do animate now
    NSTimeInterval duration = [self transitionDuration:transitionContext];
    [UIView animateWithDuration:duration
                          delay:0.0
         usingSpringWithDamping:0.6
          initialSpringVelocity:0.0
                        options:UIViewAnimationOptionCurveLinear
                     animations:^{
                         toVC.view.frame = finalFrame;
                     } completion:^(BOOL finished) {
                         // 5. Tell context that we completed.
                         [transitionContext completeTransition:YES];
                     }];
    
    
}


@end

解释一下这个实现：

 

1.我们首先需要得到参与切换的两个ViewController的信息，使用context的方法拿到它们的参照；

 

2.对于要呈现的VC，我们希望它从屏幕下方出现，因此将初始位置设置到屏幕下边缘；

 

3.将view添加到containerView中；

 

4.开始动画。这里的动画时间长度和切换时间长度一致，都为0.8s。usingSpringWithDamping的UIView动画API是iOS7新加入的，描述了一个模拟弹簧动作的动画曲线，我们在这里只做使用，更多信息可以参看相关文档；（顺便多说一句，iOS7中对UIView动画添加了一个很方便的Category，UIViewKeyframeAnimations。使用其中方法可以为UIView动画添加关键帧动画）

 

5.在动画结束后我们必须向context报告VC切换完成，是否成功（在这里的动画切换中，没有失败的可能性，因此直接pass一个YES过去）。系统在接收到这个消息后，将对VC状态进行维护。