iOS 获取view当前UIViewController的几种方法

1. 经过响应链的方法

@implementation UIView (SYGetController)

- (UIViewController *)currentController {
    UIResponder *next = [self nextResponder];
    do {
        if ([next isKindOfClass:[UIViewController class]]) {
            return (UIViewController *)next;
        }
        next = [next nextResponder];
    } while (next != nil);
    return nil;
}
@end
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2. 利用递归的思想查找当前视图控制器

+ (UIViewController *)currentViewController {
    UIViewController *vc = [UIApplication sharedApplication].keyWindow.rootViewController;
    UIViewController *currentVC = [self _findCurrentShowingViewControllerFromVC:vc];
    return currentVC;
}

+ (UIViewController *)_findCurrentShowingViewControllerFromVC:(UIViewController *)vc {
    UIViewController *currentVC;
    if ([vc presentedViewController]) {
        //判断当前根视图有没有present视图出来
        UIViewController *nextVC = [vc presentedViewController];
        currentVC = [self _findCurrentShowingViewControllerFromVC:nextVC];
        
    } else if ([vc isKindOfClass:[UITabBarController class]]) {
        //判断当前根视图是UITabBarController
        UIViewController *nextVC = [(UITabBarController*)vc selectedViewController];
        currentVC = [self _findCurrentShowingViewControllerFromVC:nextVC];
        
    } else if ([vc isKindOfClass:[UINavigationController class]]) {
        //判断当前根视图是UINavigationController
        UIViewController *nextVC = [(UINavigationController *)vc visibleViewController];
        currentVC = [self _findCurrentShowingViewControllerFromVC:nextVC];
    }else {
        currentVC = vc;
    }
    return vc;
}
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3. 遍历的方法获取

+ (UIViewController *)_findCurrentShowingViewControllerFromVC:(UIViewController *)vc {
    while (1) {
        if (vc.presentedViewController) {
            vc = vc.presentedViewController;
        } else if ([vc isKindOfClass:[UITabBarController class]]) {
            vc = ((UITabBarController *)vc).selectedViewController;
        } else if ([vc isKindOfClass:[UINavigationController class]]) {
            vc = ((UINavigationController *)vc).visibleViewController;
        } else if (vc.childViewControllers.count > 0) {
            vc = vc.childViewControllers.lastObject;
        } else {
            break;
        }
    }
    return vc;
}
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补充：presentedViewController 与 presentingViewController 假如从控制器A经过present方式跳转到B，则A的presentedViewController就是B,B的presentingViewController就是A。