How to tell if UIViewController's view is visible

Solution 1:

The view's window property is non-nil if a view is currently visible, so check the main view in the view controller:

Invoking the view method causes the view to load (if it is not loaded) which is unnecessary and may be undesirable. It would be better to check first to see if it is already loaded. I've added the call to isViewLoaded to avoid this problem.

if (viewController.isViewLoaded && viewController.view.window) {
    // viewController is visible
}

Since iOS9 it has became easier:

if viewController.viewIfLoaded?.window != nil {
    // viewController is visible
}

Or if you have a UINavigationController managing the view controllers, you could check its visibleViewController property instead.

Solution 2:

Here's @progrmr's solution as a UIViewController category:

// UIViewController+Additions.h

@interface UIViewController (Additions)

- (BOOL)isVisible;

@end


// UIViewController+Additions.m

#import "UIViewController+Additions.h"

@implementation UIViewController (Additions)

- (BOOL)isVisible {
    return [self isViewLoaded] && self.view.window;
}

@end

Solution 3:

There are a couple of issues with the above solutions. If you are using, for example, a UISplitViewController, the master view will always return true for

if(viewController.isViewLoaded && viewController.view.window) {
    //Always true for master view in split view controller
}

Instead, take this simple approach which seems to work well in most, if not all cases:

- (void)viewDidDisappear:(BOOL)animated {
    [super viewDidDisappear:animated];

    //We are now invisible
    self.visible = false;
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];

    //We are now visible
    self.visible = true;
}

Solution 4:

For those of you looking for a Swift 2.2 version of the answer:

if self.isViewLoaded() && (self.view.window != nil) {
     // viewController is visible
}

and Swift 3:

if self.isViewLoaded && (self.view.window != nil) {
         // viewController is visible
}

Solution 5:

For over-full-screen or over-context modal presentation, "is visible" could mean it is on top of the view controller stack or just visible but covered by another view controller.

To check if the view controller "is the top view controller" is quite different from "is visible", you should check the view controller's navigation controller's view controller stack.

I wrote a piece of code to solve this problem:

extension UIViewController {
    public var isVisible: Bool {
        if isViewLoaded {
            return view.window != nil
        }
        return false
    }

    public var isTopViewController: Bool {
        if self.navigationController != nil {
            return self.navigationController?.visibleViewController === self
        } else if self.tabBarController != nil {
            return self.tabBarController?.selectedViewController == self && self.presentedViewController == nil
        } else {
            return self.presentedViewController == nil && self.isVisible
        }
    }
}