開發(fā)項目過程中蚓挤，有需要獲取當(dāng)前正在展示的控制器的需求磺送。本來想用響應(yīng)鏈的思路來實現(xiàn)驻子，發(fā)現(xiàn)會有很多問題。后面發(fā)現(xiàn)可以通過控制器的入棧方式來解決這個問題册着。

1. 控制器入棧方式拴孤，示例代碼如下：

///獲取當(dāng)前活動的控制器
+ (UIViewController *)getCurrentActivityViewController {
    UIWindow *window = [UIApplication sharedApplication].delegate.window;
    NSLog(@"window level: %.0f", window.windowLevel);
    if (window.windowLevel != UIWindowLevelNormal) {
        NSArray *windows = [[UIApplication sharedApplication] windows];
        for (UIWindow * tmpWin in windows) {
            if (tmpWin.windowLevel == UIWindowLevelNormal) {
                window = tmpWin;
                break;
            }
        }
    }
    
    //從根控制器開始查找
    UIViewController *rootVC = window.rootViewController;
    UIViewController *activityVC = nil;
    
    while (true) {
        if ([rootVC isKindOfClass:[UINavigationController class]]) {
            activityVC = [(UINavigationController *)rootVC visibleViewController];
        } else if ([rootVC isKindOfClass:[UITabBarController class]]) {
            activityVC = [(UITabBarController *)rootVC selectedViewController];
        } else if (rootVC.presentedViewController) {
            activityVC = rootVC.presentedViewController;
        } else if ([rootVC isKindOfClass:[RTContainerController class]]) {
            activityVC = [(RTContainerController *)rootVC contentViewController];
        } else {
            break;
        }
        
        rootVC = activityVC;
    }
    
    return activityVC;
}

上面的代碼中的RTContainerController是我們項目中用到的 RTRootNavigationController 框架，如果項目中沒有用到的可以把上面對應(yīng)判斷項去掉甲捏。

2. 響應(yīng)鏈的方式（有問題演熟，思路可以參考）

/// 獲取當(dāng)前活動的控制器
+ (UIViewController *)getCurrentActivityViewController {
    UIViewController *result = nil;
    
    UIWindow *window = [UIApplication sharedApplication].delegate.window;
    NSLog(@"window level: %.0f", window.windowLevel);
    if (window.windowLevel != UIWindowLevelNormal) {
        NSArray *windows = [[UIApplication sharedApplication] windows];
        for (UIWindow * tmpWin in windows) {
            if (tmpWin.windowLevel == UIWindowLevelNormal) {
                window = tmpWin;
                break;
            }
        }
    }
    
    //通過響應(yīng)鏈來找到當(dāng)前View的控制器
    UIView *rootVCView = window.rootViewController.view;
    UIView *lastView = [self getLastSubviewsWithView:rootVCView];
    NSLog(@"lastView = %@", lastView);
    id nextResponder = [lastView nextResponder];
    while (nextResponder) {
        if ([nextResponder isKindOfClass:[UIViewController class]]) {
            break;
        } else if ([nextResponder isKindOfClass:[UIView class]]) {
            nextResponder = [nextResponder nextResponder];
        } else if ([nextResponder isKindOfClass:[UIApplication class]]) {
            nextResponder = nil;
            break;
        }
    }
    
    if (nextResponder != nil) {
        result = nextResponder;
    } else {
        result = window.rootViewController;
    }
    
    NSLog(@"當(dāng)前最前面的活動的控制器是: %@", result);
    return result;
}

/// 獲取View的最底層子View
+ (UIView *)getLastSubviewsWithView:(UIView *)view {
    UIView *lastView = view;
    NSMutableString *viewString = [NSMutableString string];
    while (lastView.subviews.count != 0) {
        [viewString appendFormat:@"%@=>", NSStringFromClass(lastView.class)];
        lastView = lastView.subviews.lastObject;
    }
    [viewString appendFormat:@"%@", NSStringFromClass(lastView.class)];
    NSLog(@"查找最底層的View的過程是: %@", viewString);
    return lastView;
}

3. 參考

iOS 獲得屏幕正在顯示的Controller（自定義的控制器）的實用方法