session-ios/Signal/src/ViewControllers/OWSNavigationController.m

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//
// Copyright (c) 2017 Open Whisper Systems. All rights reserved.
//
#import "OWSNavigationController.h"
// We use a category to expose UINavigationController's private
// UINavigationBarDelegate methods.
@interface UINavigationController (OWSNavigationController) <UINavigationBarDelegate>
@end
#pragma mark -
@interface OWSNavigationController () <UIGestureRecognizerDelegate>
@end
#pragma mark -
@implementation OWSNavigationController
- (void)viewDidLoad
{
[super viewDidLoad];
self.interactivePopGestureRecognizer.delegate = self;
}
#pragma mark - UINavigationBarDelegate
// All UINavigationController serve as the UINavigationBarDelegate for their navbar.
// We override shouldPopItem: in order to cancel some back button presses - for example,
// if a view has unsaved changes.
- (BOOL)navigationBar:(UINavigationBar *)navigationBar shouldPopItem:(UINavigationItem *)item
{
OWSAssert(self.interactivePopGestureRecognizer.delegate == self);
UIViewController *topViewController = self.topViewController;
// wasBackButtonClicked is YES if the back button was pressed but not
// if a back gesture was performed or if the view is popped programmatically.
BOOL wasBackButtonClicked = topViewController.navigationItem == item;
BOOL result = YES;
if (wasBackButtonClicked) {
if ([topViewController conformsToProtocol:@protocol(OWSNavigationView)]) {
id<OWSNavigationView> navigationView = (id<OWSNavigationView>)topViewController;
result = ![navigationView shouldCancelNavigationBack];
}
}
// If we're not going to cancel the pop/back, we need to call the super
// implementation since it has important side effects.
if (result) {
// NOTE: result might end up NO if the super implementation cancels the
// the pop/back.
result = [super navigationBar:navigationBar shouldPopItem:item];
}
return result;
}
#pragma mark - UIGestureRecognizerDelegate
// We serve as the UIGestureRecognizerDelegate of the interactivePopGestureRecognizer
// in order to cancel some "back" gestures - for example,
// if a view has unsaved changes.
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
UIViewController *topViewController = self.topViewController;
if ([topViewController conformsToProtocol:@protocol(OWSNavigationView)]) {
id<OWSNavigationView> navigationView = (id<OWSNavigationView>)topViewController;
return ![navigationView shouldCancelNavigationBack];
} else {
return YES;
}
}
@end