iOS 获取当前正在显示的ViewController

iOS 获取当前正在显示的ViewController,方法有如下几种:

1:从UIWindow中获取

#import "UIWindow+SHHelper.h"

@implementation UIWindow (SHHelper)

- (UIViewController*)sh_topMostController
{
    //  getting rootViewController
    UIViewController *topController = [self rootViewController];
    
    //  Getting topMost ViewController
    while ([topController presentedViewController]) topController = [topController presentedViewController];
    
    //  Returning topMost ViewController
    return topController;
}

- (UIViewController*)sh_currentViewController;
{
    UIViewController *currentViewController = [self sh_topMostController];
    
    while ([currentViewController isKindOfClass:[UINavigationController class]] && [(UINavigationController*)currentViewController topViewController])
        currentViewController = [(UINavigationController*)currentViewController topViewController];
    
    return currentViewController;
}

@end

2:从UIView里面获取

//满足一个日常的需求:在UITableviewcell里面的UIView模块里面，调用self.navigationcontroller pushviewcontroller推入一个新的viewcontroller，需要获取其上层的UIViewcontroller, 可以使用下面的方法:
- (UIViewController *)sh_viewController
{
    UIResponder *responder = self;
    while ((responder = [responder nextResponder])){
        if ([responder isKindOfClass: [UIViewController class]]){
            return (UIViewController *)responder;
        }
    }
    return nil;
}

3:从 UIViewController 中获取

#import "UIViewController+SHHelper.h"

@implementation UIViewController (SHHelper)

- (UIViewController*)sh_topMostController
{
    UIViewController *topController = self ;
    
    while ([self presentedViewController])
          topController = [topController presentedViewController];
    
    return topController;
}

- (UIViewController*)sh_currentViewController;
{
    UIViewController *currentViewController = [self sh_topMostController];
    
    while ([currentViewController isKindOfClass:[UINavigationController class]] && [(UINavigationController*)currentViewController topViewController])
        currentViewController = [(UINavigationController*)currentViewController topViewController];
    
    return currentViewController;
}

//我们在非视图类中想要随时展示一个view时，需要将被展示的view加到当前view的子视图，或用当前view presentViewController，或pushViewContrller，这些操作都需要获取当前正在显示的ViewController。
//获取当前view的UIViewController
+ (UIViewController *)sh_currentViewControllerFromcurrentView{
    
    UIViewController *result = nil;
    
    // 1. get current window
    UIWindow * window = [[UIApplication sharedApplication] keyWindow];
    if (window.windowLevel != UIWindowLevelNormal) {
        NSArray *windows = [[UIApplication sharedApplication] windows];
        for(UIWindow * tempWindow in windows) {
            if (tempWindow.windowLevel == UIWindowLevelNormal) {
                window = tempWindow;
                break;
            }
        }
    }
    
    // 2. get current View Controller
    UIView *frontView = [[window subviews] objectAtIndex:0];
    id nextResponder = [frontView nextResponder];
    if ([nextResponder isKindOfClass:[UIViewController class]]) {
        result = nextResponder;
    } else {
        result = window.rootViewController;
    }
    return result;
}

//获取当前屏幕中present出来的viewcontroller。
- (UIViewController *)getPresentedViewController
{
    UIViewController *appRootVC = [UIApplication sharedApplication].keyWindow.rootViewController;
    UIViewController *topVC = appRootVC;
    if (topVC.presentedViewController) {
        topVC = topVC.presentedViewController;
    }
    
    return topVC;
}

@end