ios - 当前可见 View Controller 检查

Question

我正在从我的 AppDelegate 类检查我的 ParentEndViewController 当前是否是可见类。

UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard_iPhone" bundle: nil];  
ParentEndViewController *parent = [storyboard instantiateViewControllerWithIdentifier:@"ParentEndViewController"];
 if (parent.isViewLoaded && parent.view.window){
         UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:displayName
                                                            message:body
                                                           delegate:nil
                                                  cancelButtonTitle:@"Ok"
                                                  otherButtonTitles:nil];
        [alertView show];
        NSLog(@"current view is parent!");
    }
    else{
        NSLog(@"current view is not parent!");
    }

正在打印 current view is not parent!”。但我确信我的应用程序上运行的当前 View 是 ParentEndViewController，即它应该打印 当前 View 是父 View !。

问题出在哪里？

Answer 1

问题是当你调用[storyboard instantiateViewControllerWithIdentifier:@"ParentEndViewController"];时，你实例化了一个ParentEndViewController的新对象，这个实例与你的 Root View Controller 的实例。如果您在应用程序委托(delegate)中检查应用程序的 Root View Controller ，您应该尝试

if([self.window.rootViewController isKindOfClass:[ParentEndViewController class]]) {
    NSLog(@"Luke I'm your father");
}
else {
    NSLog(@"Sorry bro, somebody else is the parent");
}

如果您正在检查导航 Controller 的最后一个 View Controller ，您应该尝试类似的方法:

UIViewController *lastViewController = [[self.navigationController viewControllers] lastObject];

 if([lastViewController isKindOfClass:[ParentEndViewController class]) {
       NSLog(@"Luke I'm your father");
 }
 else {
     NSLog(@"Sorry bro, somebody else is the parent");
 }