处理两个警报视图

Question

我正在申请

1) 我显示一个警报视图来接受或拒绝来电....

2) 但是，如果呼叫者自己取消了呼叫，则会显示一条警报，说明呼叫者已取消呼叫。

我的问题是，如果在我接受之前取消呼叫，警报视图会堆叠，并且在警报视图更近的位置（2）我仍然可以看到警报视图（1），因为我的要求是直接显示查看任何警报视图的更近的位置。

我已经创建了一种生成警报视图的方法，我给警报视图提供了差异标签

-(void)generateMessage:(const char*)msg Title:(const char*)title withAcceptButton:(bool)doAddAcceptButton Tag:(int)tag{

dispatch_async(dispatch_get_main_queue(), ^{

                 // We are now back on the main thread
                 UIAlertView *alertView = [[UIAlertView alloc] >init];
                //add button

                 if(doAddAcceptButton==true)
                 {
                     [alertView  addButtonWithTitle:@"OK"];
                     [alertView addButtonWithTitle:@"Cancel"];
                     alertView.cancelButtonIndex=1;

                 }
                 else {
                     [alertView  addButtonWithTitle:@"OK"];
                     alertView.cancelButtonIndex=0;
                 }

                 //add tag
                 [alertView setTag:tag];

                 //add title
                 if(title==NULL)
                 {
                     [alertView setTitle:@"MESSAGE"];
                 }
                 else {
                     NSMutableString *head = [[NSMutableString >alloc] initWithCString:title
                                                                             >encoding:NSUTF8StringEncoding];
                     [alertView setTitle:head];
                     [head release];
                 }


                 if(msg==NULL)
                 {
                     [alertView setMessage:@"ERROR"];
                 }
                 else {
                     NSMutableString *body = [[NSMutableString >alloc] initWithCString:msg
                                                                             >encoding:NSUTF8StringEncoding];
                     [alertView setMessage:body];
                     [body release];
                 }
                 [alertView setDelegate:self];
                 [alertView show];
                 [alertView release];


             });

}

Answer 1

只需保留对警报视图的引用即可。这样，如果第一个仍在显示，您可以在显示第二个之前清除它。比如：

.h 文件：

@interface ViewController : UIViewController <UIAlertViewDelegate> {
  UIAlertView * _alertView1;
  UIAlertView * _alertView2;
}

.m 文件：

- (void)viewDidLoad; {
  [super viewDidLoad];
  _alertView1 = [[UIAlertView alloc] initWithTitle:@"Alert 1" message:@"A New call!" delegate:self cancelButtonTitle:@"Deny" otherButtonTitles:@"Accept", nil];
  _alertView2 = [[UIAlertView alloc] initWithTitle:@"Alert 2" message:@"The Call was cancelled!" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
}

- (void)callWasCancelled; { // This would be the method where the second AlertView is called.
  if(_alertView1.isVisible){
    [_alertView1 dismissWithClickedButtonIndex:0 animated:YES];
  }
  [_alertView2 show];
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex; {
  if(alertView == _alertView1){
    if(buttonIndex == 1){
      // Accept the call!
    }
  }
}

希望有帮助！

Answer 2

您可以使用通知来实现这一点。当您意识到呼叫已被取消时，发出通知。处理通知时，关闭第一个 UIAlertView：

- (void)callCancelled {
    // Fire the notification
    [[NSNotificationCenter defaultCenter] postNotificationName:@"CallCancelled" 
                                                        object:nil];   
}

处理“CallCancelled”通知：

[NSNotificationCenter defaultCenter] addObserver:self 
                                        selector:@selector(handleCancelNotification:) 
                                            name:@"CallCancelled" 
                                          object:nil];

- (void)handleCancelNotification:(id)object {
  // Dismiss the first AlertView.
  [alertView dissmissWithClickedButtonIndex:-1 animated:YES];
}

Answer 3

- (void)viewDidLoad
{
    [super viewDidLoad];
    UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"Confirm" message:@"Do you pick Yes or No?" delegate:self cancelButtonTitle:@"Yes" otherButtonTitles:@"No", nil];
    [alert setDelegate:self];
    [alert show];
    [alert release];
    // Do any additional setup after loading the view, typically from a nib.
}


- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    if (buttonIndex == 0 && [alertView.title isEqualToString:@"Confirm"])
    {
        UIAlertView *alert1=[[UIAlertView alloc]initWithTitle:@"Call is Cancelled" message:@"" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
        [alert1 setDelegate:self];
        [alert1 show];
        [alert1 release];

    }
}

Answer 4

实际上，最好重新设计您的应用程序以避免 2 个 alertViews 显示一个在另一个顶部的可能性。