如何呈现viewController，我仍然可以看到后台viewController

Question

例如，当我呈现UIActivityViewController或UIAlertController时，我仍然可以看到后台viewController，我不想在viewContollerA中嵌入viewControllerB。

Answer 1

[self presentViewController:viewControllerHere animated:YES completion:nil];

Answer 2

你可以为UIAlertController实现这样的实现

    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Title" message:@"Message" preferredStyle:UIAlertControllerStyleAlert];
    UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"Cancel " style:UIAlertActionStyleCancel handler:^(UIAlertAction * action) {
        NSLog(@"cancel");
    }];
    [alertController addAction:cancelAction];
    [self presentViewController: alertController animated:YES completion:nil];