UIViewControllerAnimatedTransitioning Example

gistfile1.txt

//
//  LFSlideTransitionAnimator.m
//  Longform
//
//  Created by Benjamin Jackson on 9/16/13.
//  Copyright (c) 2013 Longform. All rights reserved.
//

#import <Foundation/Foundation.h>

typedef enum _LFSlideTransitionDirection {
    LFSlideTransitionDirectionLeft,
    LFSlideTransitionDirectionRight
} LFSlideTransitionDirection;

@interface LFSlideTransitionAnimator : NSObject <UIViewControllerAnimatedTransitioning>
@property (nonatomic) CGFloat viewWidth;
@property (nonatomic) BOOL isPresenting;
@property (nonatomic) LFSlideTransitionDirection transitionDirection;
@end

static const NSTimeInterval AnimationDuration = 0.5;
static const CGFloat DefaultViewWidth = 320;

#import "LFSlideTransitionAnimator.h"

@implementation LFSlideTransitionAnimator

- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext {
    return AnimationDuration;
}

- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext {
    if (!self.viewWidth) {
        self.viewWidth = DefaultViewWidth;
    }
    UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    
    CGFloat startX = self.transitionDirection == LFSlideTransitionDirectionLeft ? -1 * self.viewWidth : CGRectGetWidth(fromVC.view.bounds);
    CGRect startFrame  = CGRectMake(startX, 0, self.viewWidth, fromVC.view.bounds.size.height);
    CGRect transformedStartFrame =  [[transitionContext containerView] convertRect:startFrame fromView:fromVC.view];
    
    CGFloat endX = self.transitionDirection == LFSlideTransitionDirectionLeft ? 0 : CGRectGetWidth(fromVC.view.bounds) - self.viewWidth;
    CGRect endFrame = CGRectMake(endX, 0, self.viewWidth, fromVC.view.bounds.size.height);
    CGRect transformedEndFrame =  [[transitionContext containerView] convertRect:endFrame fromView:fromVC.view];
    
    if (self.isPresenting) {
        [transitionContext.containerView addSubview:fromVC.view];
        [transitionContext.containerView addSubview:toVC.view];
        
        toVC.view.frame = transformedStartFrame;
        [UIView animateWithDuration:AnimationDuration
                              delay:0
             usingSpringWithDamping:0.8
              initialSpringVelocity:0.5
                            options:UIViewAnimationOptionCurveEaseOut
                         animations:^{
            toVC.view.frame = transformedEndFrame;

        } completion:^(BOOL finished) {
            [transitionContext completeTransition:YES];
        }];
    }
    else {
        [transitionContext.containerView addSubview:toVC.view];
        [transitionContext.containerView addSubview:fromVC.view];
        
        [UIView animateWithDuration:AnimationDuration
                              delay:0
             usingSpringWithDamping:0.8
              initialSpringVelocity:0.5
                            options:UIViewAnimationOptionCurveEaseOut
                         animations:^{
            fromVC.view.frame = transformedStartFrame;
        } completion:^(BOOL finished) {
            [transitionContext completeTransition:YES];
        }];
    }
}

@end