如何通过IOS Swift中的任何后台进程获取当前的viewcontroller

Question

How to check in which viewcontroller user currently have by any background process so that action can be taken based on the viewcontroller. Currently I am using swift 2.3

Thanks, Kamal

Answer 1

Here's a swift extension of UIApplication for finding the top view controller

extension UIApplication
{
    class func topViewController(_ base: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController?
    {
        if let nav = base as? UINavigationController
        {
            let top = topViewController(nav.visibleViewController)
            return top
        }

        if let tab = base as? UITabBarController
        {
            if let selected = tab.selectedViewController
            {
                let top = topViewController(selected)
                return top
            }
        }

        if let presented = base?.presentedViewController
        {
            let top = topViewController(presented)
            return top
        }
        return base
    }
}

Invoke with

let topController = UIApplication.topViewController()

Answer 2

You can find top view controller using below method

- (UIViewController *)topViewController{
    return [self topViewController:[UIApplication sharedApplication].keyWindow.rootViewController];
}
- (UIViewController *)topViewController:(UIViewController *)rootViewController{
    if(rootViewController.presentedViewController == nil){
        return rootViewController;
    }
    if ([rootViewController.presentedViewController isMemberOfClass:[UINavigationController class]]) {
        UINavigationController *navigationController = (UINavigationController *)rootViewController.presentedViewController;
        UIViewController *lastViewController = [[navigationController viewControllers] lastObject];
        return [self topViewController:lastViewController];
    }
    UIViewController *presentedViewController = (UIViewController *)rootViewController.presentedViewController;
    return [self topViewController:presentedViewController];
}

You can create a category using this method which I've already done but on my Mac, I'm typing this on my phone sorry for any bad formatting.

After you create a category call from anywhere

[[UIApplication sharedApplication].keyWindow.rootViewController] topViewController];

I'll add this category when I get back to my Mac

EDIT

Heres the category:

@interface UIViewController (TopViewController)
- (UIViewController *)topViewController;
@end



#import "UIViewController+TopViewController.h"

@implementation UIViewController (TopViewController)

- (UIViewController *)topViewController {
    return [self topViewController:[UIApplication sharedApplication].keyWindow.rootViewController];
}

- (UIViewController *)topViewController:(UIViewController *)rootViewController
{
    if (rootViewController.presentedViewController == nil) {
        return rootViewController;
    }
    if ([rootViewController.presentedViewController isMemberOfClass:[UINavigationController class]]) {
        UINavigationController *navigationController = (UINavigationController *)rootViewController.presentedViewController;
        UIViewController *lastViewController = [[navigationController viewControllers] lastObject];
        return [self topViewController:lastViewController];
    }
    UIViewController *presentedViewController = (UIViewController *)rootViewController.presentedViewController;
    return [self topViewController:presentedViewController];
}

@end

Forgot to mention i've got this method from here