Custom leftBarButtonItem and interactivePopGestureRecognizer Freeze

UINavigationController+PopGesture.m

#import <objc/runtime.h>

@implementation UINavigationController (PopGesture)

+ (void)load {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        Class class = [self class];

        // When swizzling a class method, use the following:
        // Class class = object_getClass((id)self);

        SEL originalSelector = @selector(pushViewController:animated:);
        SEL swizzledSelector = @selector(xxx_pushViewController:animated:);

        Method originalMethod = class_getInstanceMethod(class, originalSelector);
        Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);

        BOOL didAddMethod =
        class_addMethod(class,
                        originalSelector,
                        method_getImplementation(swizzledMethod),
                        method_getTypeEncoding(swizzledMethod));

        if (didAddMethod) {
            class_replaceMethod(class,
                                swizzledSelector,
                                method_getImplementation(originalMethod),
                                method_getTypeEncoding(originalMethod));
        } else {
            method_exchangeImplementations(originalMethod, swizzledMethod);
        }
    });
}

#pragma mark - Method Swizzling

- (void)xxx_pushViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    NSLog(@"xxx_pushViewController: %@", self);
    if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)])
        self.interactivePopGestureRecognizer.enabled = NO;

    [self xxx_pushViewController:viewController animated:animated];
}

@end