问题
某些时候，需要随时弹出的界面在最顶层。例如:每个接口都可能返回鉴权失败，需要重新登录的登录界面或者手势解锁界面。
解决方案
获取到当前最顶层Controller
#import <UIKit/UIKit.h>
@(原创整理)interface UIViewController (Utils)
+(UIViewController*) currentViewController;
@end
.m
#import "UIViewController+Utils.h"
@implementation UIViewController (Utils)
+(UIViewController*) findBestViewController:(UIViewController*)vc {
if (vc.presentedViewController) {
// Return presented view controller
return [UIViewController findBestViewController:vc.presentedViewController];
} else if ([vc isKindOfClass:[UISplitViewController class]]) {
// Return right hand side
UISplitViewController* svc = (UISplitViewController*) vc;
if (svc.viewControllers.count > 0)
return [UIViewController findBestViewController:svc.viewControllers.lastObject];
else
return vc;
} else if ([vc isKindOfClass:[UINavigationController class]]) {
// Return top view
UINavigationController* svc = (UINavigationController*) vc;
if (svc.viewControllers.count > 0)
return [UIViewController findBestViewController:svc.topViewController];
else
return vc;
} else if ([vc isKindOfClass:[UITabBarController class]]) {
// Return visible view
UITabBarController* svc = (UITabBarController*) vc;
if (svc.viewControllers.count > 0)
return [UIViewController findBestViewController:svc.selectedViewController];
else
return vc;
} else {
// Unknown view controller type, return last child view controller
return vc;
}
}
+(UIViewController*) currentViewController {
// Find best view controller
UIViewController* viewController = [UIApplication sharedApplication].keyWindow.rootViewController;
return [UIViewController findBestViewController:viewController];
}
@end
实现细节总有遗漏，有时取不对，一般我采用下一种办法
重起一个windows
原理就是多windows机制，在当前window之上新建一个windows，可以保证Controller在最上层。跟UIAlertView显示机制一致。当然没UIAlertView级别高，当有UIAlertView弹出时候，再弹出新起的Windows时，UIAlertView还在最上。
具体使用开源库LNWindowManager即可。
创建并显示一个Windows
UIWindow* window = [LNWindowManager templateWindowForName:@"demo"];
window.rootViewController = nvc;
[[LNWindowManager sharedWindowManager].topWindow presentWindow:window animated:YES completion:nil];
移除windows
[[LNWindowManager sharedWindowManager].topWindow.presentingWindow dismissWindow:[LNWindowManager sharedWindowManager].topWindow animated:YES completion:nil];
Demo
别人git上的Demo
