BufferedNavigationController.m

/* Copyright (c) 2011 Andrew Armstrong <phplasma at gmail dot com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#import "BufferedNavigationController.h"

@implementation BufferedNavigationController
@synthesize transitioning = _transitioning;
@synthesize stack = _stack;

- (void)viewDidLoad {
    [super viewDidLoad];

    self.delegate = self;
    self.stack = [[NSMutableArray alloc] init];
}

- (UIViewController *)popViewControllerAnimated:(BOOL)animated {
    @synchronized(self.stack) {
        if (self.transitioning) {
            void (^codeBlock)(void) = [^{
                [super popViewControllerAnimated:animated];
            } copy];
            [self.stack addObject:codeBlock];

            // We cannot show what viewcontroller is currently animated now
            return nil;
        } else {
            return [super popViewControllerAnimated:animated];
        }
    }
}

- (NSArray *)popToRootViewControllerAnimated:(BOOL)animated {
    @synchronized(self.stack) {
        if (self.transitioning) {
            void (^codeBlock)(void) = [^{
                [super popToRootViewControllerAnimated:animated];
            } copy];
            [self.stack addObject:codeBlock];

            // We cannot show what viewcontroller is currently animated now
            return nil;
        } else {
            return [super popToRootViewControllerAnimated:animated];
        }
    }
}

- (NSArray*) popToViewController:(UIViewController *)viewController animated:(BOOL)animated {
    @synchronized(self.stack) {
        if (self.transitioning) {
            void (^codeBlock)(void) = [^{
                [super popToViewController:viewController animated:animated];
            } copy];
            [self.stack addObject:codeBlock];

            // We cannot show what viewcontroller is currently animated now
            return nil;
        } else {
            return [super popToViewController:viewController animated:animated];
        }
    }
}

- (void)setViewControllers:(NSArray *)viewControllers animated:(BOOL)animated {
    @synchronized(self.stack) {
        if (self.transitioning) {
            // Copy block so its no longer on the (real software) stack
            void (^codeBlock)(void) = [^{
                [super setViewControllers:viewControllers animated:animated];
            } copy];

            // Add to the stack list and then release
            [self.stack addObject:codeBlock];
        } else {
            [super setViewControllers:viewControllers animated:animated];
        }
    }
}

- (void) pushCodeBlock:(void (^)())codeBlock{
    @synchronized(self.stack) {
        [self.stack addObject:[codeBlock copy]];

        if (!self.transitioning)
            [self runNextBlock];
    }
}

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated {
    @synchronized(self.stack) {
        if (self.transitioning) {
            void (^codeBlock)(void) = [^{
                [super pushViewController:viewController animated:animated];
            } copy];
            [self.stack addObject:codeBlock];
        } else {
            [super pushViewController:viewController animated:animated];
        }
    }
}

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated {

    @synchronized (self.stack) {
        self.transitioning = true;
        
        if ([navigationController.topViewController respondsToSelector:@selector(transitionCoordinator)]) {
            id <UIViewControllerTransitionCoordinator> transitionCoordinator = navigationController.topViewController.transitionCoordinator;
            [transitionCoordinator notifyWhenInteractionEndsUsingBlock:^(id <UIViewControllerTransitionCoordinatorContext> context) {
                if ([context isCancelled]) {
                    @synchronized (self.stack) {
                        self.transitioning = false;
                    }
                }
            }];
        }
    }
}

- (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated {

    @synchronized(self.stack) {
        self.transitioning = false;

        [self runNextBlock];
    }
}

- (void) runNextBlock {
    if (self.stack.count == 0)
        return;

    void (^codeBlock)(void) = [self.stack objectAtIndex:0];

    // Execute block, then remove it from the stack (which will dealloc)
    codeBlock();

    [self.stack removeObjectAtIndex:0];
}

@end