当我仍然可以看到背景viewController时，如何呈现viewController

Question

例如，当我显示UIActivityViewController或UIAlertController时，仍然可以看到背景viewController，并且我不想在viewContollerA中嵌入viewControllerB。

Answer 1

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

Answer 2

您可以为UIAlertController这样实现

    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];