//  SwipeView.h
#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>

@interface SwipeView : UIView {
    CGPoint startTouchPosition;
    NSString *dirString;
    UIViewController *host;
}

- (void) setHost: (UIViewController *) aHost;

@end

//  SwipeView.m
#import "SwipeView.h"

@implementation SwipeView

- (id)initWithFrame:(CGRect)frame {
    if ((self = [super initWithFrame:frame])) {
        // Initialization code
    }
    return self;
}

- (void) setHost: (UIViewController *) aHost
{
    host = aHost;
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { 
    UITouch *touch = [touches anyObject]; 
    startTouchPosition = [touch locationInView:self]; 
    dirString = NULL;
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { 
    UITouch *touch = touches.anyObject; 
    CGPoint currentTouchPosition = [touch locationInView:self]; 
    
#define HORIZ_SWIPE_DRAG_MIN 12 
#define VERT_SWIPE_DRAG_MAX 4 
    
    if (fabsf(startTouchPosition.x - currentTouchPosition.x) >= 
        HORIZ_SWIPE_DRAG_MIN && 
        fabsf(startTouchPosition.y - currentTouchPosition.y) <= 
        VERT_SWIPE_DRAG_MAX)     { 
        // Horizontal Swipe
        if (startTouchPosition.x < currentTouchPosition.x) {
            dirString = kCATransitionFromLeft;
        }
        else 
            dirString = kCATransitionFromRight;
    }
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    if (dirString) [host swipeTo:dirString];
}

@end

//  PageViewController.m
- (void) swipeTo: (NSString *) aDirection{
    UIPageControl *pageControl = [[[contentView superview] subviews] lastObject];
    
    if ([aDirection isEqualToString:kCATransitionFromRight])
    {
        if (currentPage == 5) return;
        [pageControl setCurrentPage:currentPage + 1];
    } else {
        if (currentPage == 0) return;
        [pageControl setCurrentPage:currentPage - 1];
    }
    
    [self pageTurn:pageControl];
}

- (void) pageTurn: (UIPageControl *) pageControl{
    CATransition *transition;
    int secondPage = [pageControl currentPage];
    if ((secondPage - currentPage) > 0)
        transition = [self getAnimation:@"fromRight"];
    else
        transition = [self getAnimation:@"fromLeft"];
    
    UIImageView *newView = (UIImageView *)[[contentView subviews] objectAtIndex:0];
    [newView setImage:[UIImage imageNamed:[NSString stringWithFormat:@"ipad_ wallpaper%02d.jpg", secondPage + 1]]];
    [contentView exchangeSubviewAtIndex:0 withSubviewAtIndex:1];
    [[contentView layer] addAnimation:transition forKey:@"transitionView Animation"];
    
    currentPage = [pageControl currentPage];
}