Question

我正在尝试实现此方法：

(\\w+)(?:\\)+)

在我声明的头文件中：UIAlertController * alert;

但是我得到一个没有可见的选择器错误界面？那是为什么？

Answer 1

试试这个：

UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"No network connection" message:@"You must be connected to the internet to use this app." preferredStyle:UIAlertControllerStyleAlert];

    [alert addAction:[UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {

    }]];

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

Answer 2

你得到了＃34;选择器错误没有可见的界面＆＃34; 因为UIAlertController在其类中没有 initWithTitle：message：delegate：cancelButtonTitle：otherButtonTitles 方法;它在UIAlertView类中可用。

UIAlertView的实际实现[在iOS 9.0中已弃用];

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"No network connection"
                                                    message:@"You must be connected to the internet to use this app."]
                                                   delegate:self
                                          cancelButtonTitle:@"OK"
                                          otherButtonTitles:nil];
[alert show];

要在单击按钮时执行操作，请遵循UIAlertViewDelegate协议：

@interface YourViewController : UIViewController <UIAlertViewDelegate>

＆安培;实现这个委托方法：

- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex {
    // the user clicked OK
    if (buttonIndex == 0) {
        // do something here...
    }
}

您可以使用UIAlertController;

UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"No network connection" 
                            message:@"You must be connected to the internet to use this app." 
                     preferredStyle:UIAlertControllerStyleAlert];

[alert addAction:[UIAlertAction actionWithTitle:@"OK" 
                                          style:UIAlertActionStyleDefault
                                        handler:^(UIAlertAction * _Nonnull action) {
                                                   //perform Action   }]];
[self presentViewController:alert animated:YES completion:nil];

没有可见的选择器错误接口，但在标头中声明？

2 个答案: