如何在显示 2 个警报之间暂停代码

Question

我有一些 iOS 代码需要能够显示 2 个背靠背警报。当用户在第一个警报上单击 "ok" 时，我需要显示第二个警报。因为显示警报不会 "pause" 代码，所以我的第二个警报试图与我的第一个警报几乎同时显示，但事情中断了（第二个警报没有显示）。

我需要的是一种在显示第一个警报时暂停代码的方法。一旦用户在第一个警报上单击 "ok"，它就可以显示第二个警报。

在进入第二个警报之前等待第一个警报完成的正确方法是什么？

这是我的完整代码，希望对您有帮助。每个警报都由一个条件触发。如果这两个条件都成立，那么我就会遇到我所描述的背靠背警报问题。

    UIAlertController* alert;
    UIAlertAction* defaultAction;
    CLAuthorizationStatus status = [CLLocationManager authorizationStatus];
    if(status != kCLAuthorizationStatusAuthorizedAlways) {
        alert = [UIAlertController alertControllerWithTitle:@"Warning"
                                                    message:@"Reminder will not work unless you enable 'Always' location."
                                             preferredStyle:UIAlertControllerStyleAlert];

        defaultAction = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault
                                               handler:^(UIAlertAction * action) {}];


        [alert addAction:defaultAction];
        [self presentViewController:alert animated:YES completion:nil];

    }


    UIUserNotificationSettings *settings = [[UIApplication sharedApplication] currentUserNotificationSettings];
    if(settings.types==0) {
        alert = [UIAlertController alertControllerWithTitle:@"Warning"
                                                    message:@"Reminder will not work unless you enable notifications."
                                             preferredStyle:UIAlertControllerStyleAlert];

        defaultAction = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault
                                               handler:^(UIAlertAction * action) {}];

        [alert addAction:defaultAction];
        [self presentViewController:alert animated:YES completion:nil];
    }

Answer 1

您所要做的只是处理程序中的第二个警报：

UIAlertController* alert;
UIAlertAction* defaultAction;
CLAuthorizationStatus status = [CLLocationManager authorizationStatus];
if(status != kCLAuthorizationStatusAuthorizedAlways) {
    alert = [UIAlertController alertControllerWithTitle:@"Warning"
                                                message:@"Reminder will not work unless you enable 'Always' location."
                                         preferredStyle:UIAlertControllerStyleAlert];

    defaultAction = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault
                                           handler:^(UIAlertAction * action) {

        UIUserNotificationSettings *settings = [[UIApplication sharedApplication] currentUserNotificationSettings];

        if(settings.types==0) {

            inner_alert = [UIAlertController alertControllerWithTitle:@"Warning"
                                                message:@"Reminder will not work unless you enable notifications."
                                         preferredStyle:UIAlertControllerStyleAlert];

            inner_defaultAction = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault
                                           handler:^(UIAlertAction * action) {}];

            [inner_alert addAction:inner_defaultAction];
            [self presentViewController:inner_alert animated:YES completion:nil];
        }
    }];


    [alert addAction:defaultAction];
    [self presentViewController:alert animated:YES completion:nil];

}

这样，当您点击 "Ok" 时，它会调用第二次警报的代码。

Answer 2

可以在@interface中设置变量，在viewDidLoad中设置为0

@interface ViewController ()
    @property (nonatomic) int number;
@end

- (void)viewDidLoad {
    [super viewDidLoad];
    self.number = 0;

}

然后创建显示警报的函数并通过开关调用其他警报(self.number)，或者您可以再次调用 showAlert 本身。

    - (void) showAlert {

    UIAlertController *alert = [UIAlertController alertController WithTitle:@"ALERT" message:@"" preferredStyle:UIAlertControllerStyleAlert];

    UIAlertAction *okAction = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {

        switch (self.number) {
            case 0:
            self.number = 1;                
            [self secondAlert]; // other alert function
                break;
            case 1:
            [self thirdAlert];
            default:
            break;
            }
    }];
    UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"CANCEL" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {

            }];

    [alert addAction:okAction];
    [alert addAction:cancelAction];

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

如何在显示 2 个警报之间暂停代码

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