Displaying UIAlertViews Sequentially

I have several UIAlertViews that i want to display in a sequential order, and only move on to display the next UIAlertView once the previous one has been dismissed (by user clicking okay).

I know about the didDismissWithButtonIndex delegate and adding a tag, but this doesn't really help too much as there could be upto 3 UIAlertViews invoked and not necessarily in the same order everytim开发者_如何学运维e. see code:

if(condition 1){
    alert1 = // UIAlertView[[.....
    [alert1 show]
}

if(condition 2){
    alert2 = // UIAlertView[[.....
    [alert2 show]
}

if(condition 3){
    alert3 = // UIAlertView[[.....
    [alert3 show]
}

The above will just add 3 Alerts on top of each other (depending on how many conditions are met) which is not what I want. I want to be able to only show one at a time and then the next one (if there is one) after the user hits the ok button.

I had the idea of maybe adding the messages to a queue and then processing that queue removing the alert every time an alert is dismissed but i'm not sure how id go about doing that.

Any ideas would be much appreciated. Thanks

---

You could easily do it in the UIAlertView delegate method, called once an alert view is dismissed. So, UIAlertViewDelegate defines the following delegate method:

– alertView:didDismissWithButtonIndex:

Implement that method, and make sure your class is the delegate of the UIAlertViews you create. This method is the perfect place to then show the next alert based on the one being dismissed by the user.

If your requirement is "Display up to three alerts, sequentially, but not always in the same order" i'd probably put the alerts in to an array, and then in the delegate method get the next alert out of the array to show. It doesn't have to be any more complex than that really; the key thing is that the delegate method implementation is the best place to show the next alert.

Pseudo Code Example:

Define an array; NSMutableArray * alerts_;

- (void)showAlertSequence {
    if ( !alerts_ ) {
        alerts_ = [[NSMutableArray alloc] init];
    }

    [alerts_ addObjects;<My alerts>];

    [self showSequencedAlertFrom:nil];
}

- (BOOL)showSequencedAlertFrom:(UIAlertView *)sourceAlertView {

    if ( !sourceAlertView ) {
        [[alerts_ objectAtIndex:0] show];
    }
    else {
        NSInteger index = [alerts_ indexOfObject:sourceAlertView];

        if ( index < [alerts_ count] ) {
            [[alerts_ objectAtIndex:index++] show];
        }
    }

    return NO;
}

– alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)index {

    // Show the next alert or clean up if we're at the end of the sequence.
    if ( ![self showSequencedAlertFrom:alertView] ) {
        [alerts_ removeAllObjects];
    }
}   

As an aside; three sequential alerts will really annoy you users ;)

---

One thing that I've done is used block based UIAlertViews by adding a category on AlertView.

Here is the .h file

@interface UIAlertView (WithBlocks)

- (id) initWithTitle:(NSString *)title message:(NSString *)message;
- (void) addButtonWithTitle:(NSString *)title andBlock:(void(^)())block;

@end

Here is the .m file

static NSString *BUTTON_BLOCK_KEY = @"alertview-button-blocks";

@interface UIAlertView()
- (void) runBlock: (void (^)())block;
@end

@implementation UIAlertView (WithBlocks)

/**
 * Initialized an alert view with a title and message.
 */
- (id) initWithTitle:(NSString *)title message:(NSString *)message
{
    self = [self initWithTitle:title message:message delegate:nil cancelButtonTitle:nil otherButtonTitles:nil];
    if (self) {
        self.delegate = self;
        NSMutableArray *buttonBlocks = [NSMutableArray array];
        objc_setAssociatedObject(self, BUTTON_BLOCK_KEY, buttonBlocks, OBJC_ASSOCIATION_RETAIN_NONATOMIC);

    }
    return self;
}

/**
 * Adds a button with a title and a block to be executed when that button is tapped.
 */
- (void) addButtonWithTitle:(NSString *)title andBlock:(void (^)())block
{
    // Add the button
    [self addButtonWithTitle:title];
    NSMutableArray *buttonBlocks = objc_getAssociatedObject(self, BUTTON_BLOCK_KEY);
    if (!block) {
        block = ^{ /* empty block */ };
    }
    [buttonBlocks addObject:[[[block copy] retain] autorelease]];
}

- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
{
    NSMutableArray *buttonBlocks = objc_getAssociatedObject(self, BUTTON_BLOCK_KEY);
    void (^block)() = (void (^)()) [buttonBlocks objectAtIndex:buttonIndex];

    // Due to a timing issue, the current window is still the UIAlertView for a very
    // short amount of time after it has been dismissed which messes up anything
    // trying to get the current window in the blocks being run.
    // Ergo, the block is being delayed by a tiny bit. (Amount determined through limited testing)
    [self performSelector:@selector(runBlock:) withObject:block afterDelay:0.25];
}

- (void) runBlock: (void (^)())block
{
    block();
}

@end

Then you can call chain the alertviews together by the following code

 void(^continueBlock)(void) = ^{
     // Display more alertviews here
 };

 UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Title" message:@"message"];
 [alert addButtonWithTitle:@"Continue" andBlock:continueBlock];

 [alert addButtonWithTitle:@"Dismiss" andBlock:^{
   // Display more alertviews here
 }
 [alert show];
 [alert release];

---

I was looking for a solution to this problem as well. Here's the way I ended up solving it for my own app:

static BOOL alertShowing = FALSE;

UIAlertView *alert0 = [[UIAlertView alloc] initWithTitle:@"AlertView 0" message:@"This is the first alert" delegate:self cancelButtonTitle:nil otherButtonTitles:@"Yes",@"No", nil];
[alert0 setTag:0];
alertShowing = TRUE;
[alert0 show];

while (alertShowing) { 
    [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate dateWithTimeIntervalSinceNow:0.2]];
}

UIAlertView *alert1 = [[UIAlertView alloc] initWithTitle:@"AlertView 1" message:@"This is the second alert" delegate:self cancelButtonTitle:nil otherButtonTitles:@"Yes",@"No", nil];
[alert1 setTag:1];
alertShowing = TRUE;
[alert1 show];

while (alertShowing) { 
    [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate dateWithTimeIntervalSinceNow:0.2]];
}

// add some more alerts here for dramatic effect ...

Your button handler must set alertShowing = FALSE' in every exit path.

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
    // Deal with handling responses for your different alerts here.
    switch ([alertView tag]) {
        case 0:
            // handler first alert here
            break;
        case 1:
            // handler second alert here
            break;
        default:
            // etc.
            break;
    }

    alertShowing = FALSE;
}

There may be better ways to sit and spin than creating a new run loop, and there's some duplicate code that probably could be genericized better. On the plus side, it's straightforward and doesn't require a bunch of queuing logic. I'm using a #define for this pattern to keep from having to hand-type it, and it has worked fine in my case.

---

Here's how I did it using a queue of alert's like you suggested.

@property (strong, nonatomic) NSMutableArray *alertQueue;
@property (nonatomic) BOOL showingAlert;

- (void)showAlert:(UIAlertView *)alert {
  if (self.showingAlert) {
    [self.alertQueue addObject:alert];
  }
  else {
    self.showingAlert = YES;
    [alert show];
  }
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
  if ([self.alertQueue count]) {
    UIAlertView *alert = [self.alertQueue objectAtIndex:0];
    [self.alertQueue removeObjectAtIndex:0];
    [alert show];
  }
  else self.showingAlert = NO;
}

Then whenever you want to display an alert, you just create the UIAlertView and pass it to the showAlert method and it will only show up after all earlier alerts have been dismissed.