このバグを再現するには、2つのView Controllerを同時にプッシュしてみてください。または同時に押してポップします。例:
これらの呼び出しをインターセプトし、進行中に他のプッシュが発生しないようにすることで、それらを安全にするカテゴリを作成しました。コードをプロジェクトにコピーするだけで、メソッドのスウィズリングにより、問題ありません。
#import "UINavigationController+Consistent.h"
#import <objc/runtime.h>
/// This char is used to add storage for the isPushingViewController property.
static char const * const ObjectTagKey = "ObjectTag";
@interface UINavigationController ()
@property (readwrite,getter = isViewTransitionInProgress) BOOL viewTransitionInProgress;
@end
@implementation UINavigationController (Consistent)
- (void)setViewTransitionInProgress:(BOOL)property {
NSNumber *number = [NSNumber numberWithBool:property];
objc_setAssociatedObject(self, ObjectTagKey, number , OBJC_ASSOCIATION_RETAIN);
}
- (BOOL)isViewTransitionInProgress {
NSNumber *number = objc_getAssociatedObject(self, ObjectTagKey);
return [number boolValue];
}
#pragma mark - Intercept Pop, Push, PopToRootVC
/// @name Intercept Pop, Push, PopToRootVC
- (NSArray *)safePopToRootViewControllerAnimated:(BOOL)animated {
if (self.viewTransitionInProgress) return nil;
if (animated) {
self.viewTransitionInProgress = YES;
}
//-- This is not a recursion, due to method swizzling the call below calls the original method.
return [self safePopToRootViewControllerAnimated:animated];
}
- (NSArray *)safePopToViewController:(UIViewController *)viewController animated:(BOOL)animated {
if (self.viewTransitionInProgress) return nil;
if (animated) {
self.viewTransitionInProgress = YES;
}
//-- This is not a recursion, due to method swizzling the call below calls the original method.
return [self safePopToViewController:viewController animated:animated];
}
- (UIViewController *)safePopViewControllerAnimated:(BOOL)animated {
if (self.viewTransitionInProgress) return nil;
if (animated) {
self.viewTransitionInProgress = YES;
}
//-- This is not a recursion, due to method swizzling the call below calls the original method.
return [self safePopViewControllerAnimated:animated];
}
- (void)safePushViewController:(UIViewController *)viewController animated:(BOOL)animated {
self.delegate = self;
//-- If we are already pushing a view controller, we dont push another one.
if (self.isViewTransitionInProgress == NO) {
//-- This is not a recursion, due to method swizzling the call below calls the original method.
[self safePushViewController:viewController animated:animated];
if (animated) {
self.viewTransitionInProgress = YES;
}
}
}
// This is confirmed to be App Store safe.
// If you feel uncomfortable to use Private API, you could also use the delegate method navigationController:didShowViewController:animated:.
- (void)safeDidShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
//-- This is not a recursion. Due to method swizzling this is calling the original method.
[self safeDidShowViewController:viewController animated:animated];
self.viewTransitionInProgress = NO;
}
// If the user doesnt complete the swipe-to-go-back gesture, we need to intercept it and set the flag to NO again.
- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
id<UIViewControllerTransitionCoordinator> tc = navigationController.topViewController.transitionCoordinator;
[tc notifyWhenInteractionEndsUsingBlock:^(id<UIViewControllerTransitionCoordinatorContext> context) {
self.viewTransitionInProgress = NO;
//--Reenable swipe back gesture.
self.interactivePopGestureRecognizer.delegate = (id<UIGestureRecognizerDelegate>)viewController;
[self.interactivePopGestureRecognizer setEnabled:YES];
}];
//-- Method swizzling wont work in the case of a delegate so:
//-- forward this method to the original delegate if there is one different than ourselves.
if (navigationController.delegate != self) {
[navigationController.delegate navigationController:navigationController
willShowViewController:viewController
animated:animated];
}
}
+ (void)load {
//-- Exchange the original implementation with our custom one.
method_exchangeImplementations(class_getInstanceMethod(self, @selector(pushViewController:animated:)), class_getInstanceMethod(self, @selector(safePushViewController:animated:)));
method_exchangeImplementations(class_getInstanceMethod(self, @selector(didShowViewController:animated:)), class_getInstanceMethod(self, @selector(safeDidShowViewController:animated:)));
method_exchangeImplementations(class_getInstanceMethod(self, @selector(popViewControllerAnimated:)), class_getInstanceMethod(self, @selector(safePopViewControllerAnimated:)));
method_exchangeImplementations(class_getInstanceMethod(self, @selector(popToRootViewControllerAnimated:)), class_getInstanceMethod(self, @selector(safePopToRootViewControllerAnimated:)));
method_exchangeImplementations(class_getInstanceMethod(self, @selector(popToViewController:animated:)), class_getInstanceMethod(self, @selector(safePopToViewController:animated:)));
}
@end