SwipeNavigationController

SwipeNavigationController.h

//
//  SwipeNavigationController.h
//  cdNBA
//
//  Created by Jason Lee on 13-9-17.
//  Copyright (c) 2013年 Jason Lee. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface SwipeNavigationController : UINavigationController

@end

SwipeNavigationController.m

//
//  SwipeNavigationController.m
//  cdNBA
//
//  Created by Jason Lee on 13-9-17.
//  Copyright (c) 2013年 Jason Lee. All rights reserved.
//

#import "SwipeNavigationController.h"
#import <QuartzCore/QuartzCore.h>

#define KEY_WINDOW  [[UIApplication sharedApplication] keyWindow]
#define TOP_VIEW    (KEY_WINDOW.rootViewController.view)

static float originalScaleRate = 0.9;
static float originalMaskAlpha = 0.5;

@interface SwipeNavigationController ()

@property (nonatomic, strong) NSMutableArray *snapshotStack;
@property (nonatomic, strong) UIImageView *snapshotImageView;
@property (nonatomic, strong) UIView *snapshotMaskView;

@property (nonatomic, assign) CGPoint startTouch;

@end

@implementation SwipeNavigationController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)dealloc
{
    [_snapshotStack release], _snapshotStack = nil;
    [_snapshotImageView release], _snapshotImageView = nil;
    [_snapshotMaskView release], _snapshotMaskView = nil;
    //
    [super dealloc];
}

- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view.
    
    UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePanGesture:)];
    [self.view addGestureRecognizer:panGestureRecognizer];
    [panGestureRecognizer release], panGestureRecognizer = nil;
}

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

#pragma mark - capture last view's snapshot

- (UIImage *)takeSnapshot
{
    UIGraphicsBeginImageContextWithOptions(TOP_VIEW.bounds.size, TOP_VIEW.opaque, 0.0);
    [TOP_VIEW.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *snapshot = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return snapshot;
}

#pragma mark - override push

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    if (!self.snapshotStack) {
        self.snapshotStack = [[[NSMutableArray alloc] initWithCapacity:5] autorelease];
    }
    
    UIImage *snapshot = [self takeSnapshot];
    if (snapshot) [self.snapshotStack addObject:snapshot];
    
    [super pushViewController:viewController animated:animated];
}

#pragma mark - handlePanGesture

- (void)handlePanGesture:(UIPanGestureRecognizer *)panGestureRecognizer
{
    if (self.viewControllers.count <= 1) return ;
    
    CGPoint point = [panGestureRecognizer locationInView:KEY_WINDOW];
    
    if (panGestureRecognizer.state == UIGestureRecognizerStateBegan) {
        [self initSnapshot];
        
        self.snapshotImageView.image = [self.snapshotStack lastObject];
        self.snapshotImageView.hidden = NO;
        [TOP_VIEW.superview insertSubview:self.snapshotImageView belowSubview:TOP_VIEW];
        
        [UIView animateWithDuration:0.3 animations:^{
            CGRect frame = TOP_VIEW.frame;
            frame.origin.x = point.x;
            TOP_VIEW.frame = frame;
            
            [self scaleSnapshotWithXOffset:frame.origin.x];
        } completion:^(BOOL finished) {
            ;
        }];
    } else if (panGestureRecognizer.state == UIGestureRecognizerStateChanged) {
        CGRect frame = TOP_VIEW.frame;
        frame.origin.x = point.x;
        TOP_VIEW.frame = frame;
        
        [self scaleSnapshotWithXOffset:frame.origin.x];
    } else {
        [self judgeToPushOrPop];
    }
}

- (void)initSnapshot
{
    if (!self.snapshotImageView) {
        self.snapshotImageView = [[[UIImageView alloc] initWithFrame:TOP_VIEW.bounds] autorelease];
        
        if (!self.snapshotMaskView) {
            self.snapshotMaskView = [[[UIView alloc] initWithFrame:self.snapshotImageView.bounds] autorelease];
            [self.snapshotImageView addSubview:self.snapshotMaskView];
            self.snapshotMaskView.backgroundColor = [UIColor colorWithWhite:0 alpha:originalMaskAlpha];
        }
    }
    
    self.snapshotImageView.transform = CGAffineTransformMakeScale(originalScaleRate, originalScaleRate);
}

#pragma mark - judgeToPushOrPop

- (void)judgeToPushOrPop
{
    __block CGRect frame = TOP_VIEW.frame;
    if (frame.origin.x > (frame.size.width / 3)) {
        [UIView animateWithDuration:0.3 animations:^{
            frame.origin.x = frame.size.width;
            TOP_VIEW.frame = frame;
            
            [self scaleSnapshotWithXOffset:frame.origin.x];
        } completion:^(BOOL finished) {
            [self popViewControllerAnimated:NO];
            
            self.snapshotImageView.hidden = YES;
            [self.snapshotStack removeLastObject];
            
            frame.origin.x = 0;
            TOP_VIEW.frame = frame;
        }];
    } else {
        [UIView animateWithDuration:0.3 animations:^{
            frame.origin.x = 0;
            TOP_VIEW.frame = frame;
            
            [self scaleSnapshotWithXOffset:frame.origin.x];
        } completion:^(BOOL finished) {
            self.snapshotImageView.hidden = YES;
        }];
    }
}

#pragma mark - scale snapshotImageView

- (void)scaleSnapshotWithXOffset:(CGFloat)xOffset
{
    CGFloat rate = (1 - originalScaleRate) * (xOffset / TOP_VIEW.frame.size.width);
    CGFloat targetRate = originalScaleRate + rate;
    if (targetRate > 1) targetRate = 1;
    
    self.snapshotImageView.transform = CGAffineTransformMakeScale(targetRate, targetRate);
    
    [self scaleSnapshotMaskAlphaWithXOffset:xOffset];
}

- (void)scaleSnapshotMaskAlphaWithXOffset:(CGFloat)xOffset
{
    CGFloat alpha = (1 - originalMaskAlpha) * (xOffset / TOP_VIEW.frame.size.width);
    CGFloat targetAlpha = 1 - (originalMaskAlpha + alpha);
    
    self.snapshotMaskView.backgroundColor = [UIColor colorWithWhite:0 alpha:targetAlpha];
}

#pragma mark -

@end