How to present UIAlertController when not in a view controller?

Question

Scenario: The user taps on a button on a view controller. The view controller is the topmost (obviously) in the navigation stack. The tap invokes a utility class method call

Answer 1

There 2 approaches that you can use:

-Use UIAlertView or 'UIActionSheet' instead (not recommended, cause it deprecated in iOS 8 but it works now)

-Somehow remember the last view controller which is presented. Here is example.

@interface UIViewController (TopController)
+ (UIViewController *)topViewController;
@end

// implementation

#import "UIViewController+TopController.h"
#import 

static __weak UIViewController *_topViewController = nil;

@implementation UIViewController (TopController)

+ (UIViewController *)topViewController {
    UIViewController *vc = _topViewController;
    while (vc.parentViewController) {
        vc = vc.parentViewController;
    }
    return vc;
}

+ (void)load {
    [super load];
    [self swizzleSelector:@selector(viewDidAppear:) withSelector:@selector(myViewDidAppear:)];
    [self swizzleSelector:@selector(viewWillDisappear:) withSelector:@selector(myViewWillDisappear:)];
}

- (void)myViewDidAppear:(BOOL)animated {
    if (_topViewController == nil) {
        _topViewController = self;
    }

    [self myViewDidAppear:animated];
}

- (void)myViewWillDisappear:(BOOL)animated {
    if (_topViewController == self) {
        _topViewController = nil;
    }

    [self myViewWillDisappear:animated];
}

+ (void)swizzleSelector:(SEL)sel1 withSelector:(SEL)sel2
{
    Class class = [self class];

    Method originalMethod = class_getInstanceMethod(class, sel1);
    Method swizzledMethod = class_getInstanceMethod(class, sel2);

    BOOL didAddMethod = class_addMethod(class,
                                        sel1,
                                        method_getImplementation(swizzledMethod),
                                        method_getTypeEncoding(swizzledMethod));

    if (didAddMethod) {
        class_replaceMethod(class,
                            sel2,
                            method_getImplementation(originalMethod),
                            method_getTypeEncoding(originalMethod));
    } else {
        method_exchangeImplementations(originalMethod, swizzledMethod);
    }
}

@end 

Usage:

[[UIViewController topViewController] presentViewController:alertController ...];