获取当前控制器

在做项目时，有时候，会写一个工具类来对项目进行操作：
这个时候如果需要使用当前控制器去进行一些操作，比如想去present一个alertController，
这时候就需要获取到当前控制器了，下面就是获取的方法：根据每个App都是一个单例来获取当前窗口的根控制器，从而获取到所有的控制器，找到

+ (UIViewController *)getCurrentVC {

UIWindow *window = [[UIApplication sharedApplication].windows firstObject];
if (!window) {
return nil;
    }
UIView *tempView;
for (UIView *subview in window.subviews) {
if ([[subview.classForCoder description] isEqualToString:@"UILayoutContainerView"]) {
            tempView = subview;
break;
        }
    }
if (!tempView) {
        tempView = [window.subviews lastObject];
    }

id nextResponder = [tempView nextResponder];
while (![nextResponder isKindOfClass:[UIViewController class]] || [nextResponder isKindOfClass:[UINavigationController class]] || [nextResponder isKindOfClass:[UITabBarController class]]) {
        tempView =  [tempView.subviews firstObject];

if (!tempView) {
return nil;
        }
        nextResponder = [tempView nextResponder];
    }
return  (UIViewController *)nextResponder;
}

swift写法

class dynamic func getCurrentController() -> UIViewController? {

guard let window = UIApplication.shared.windows.first else {
return nil
        }

var tempView: UIView?

for subview in window.subviews.reversed() {


if subview.classForCoder.description() == "UILayoutContainerView" {

                tempView = subview

break
            }
        }

if tempView == nil {

            tempView = window.subviews.last
        }

var nextResponder = tempView?.next

var next: Bool {
return !(nextResponder is UIViewController) || nextResponder is UINavigationController || nextResponder is UITabBarController
        }

while next{

            tempView = tempView?.subviews.first

if tempView == nil {

return nil
            }

            nextResponder = tempView!.next
        }

return nextResponder as? UIViewController
    }
}

作者：乔克_叔叔
链接：http://www.jianshu.com/p/ab0cb586fc9f
來源：简书
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