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Standard operating system (OS) methods for alerts and messages can often be more accessible than something custom made, in particular for users of assistive technology. This is because standard controls:

• have traits that are understood by assistive technology such as screen readers,
• generally appear in a consistent location, and
• follow the user-defined options for font and colour.

App level and browser level errors and alerts should use operating system methods of notification. However, page/screen or content level errors and alerts may use either OS or custom notifications. Custom notifications must be perceivable.

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iOS

Use a UIAlertController to display a message box dialog that contains the error message.

iOS Example (Objective-C)

UIAlertView *messageBox = [[UIAlertView alloc] initWithTitle: NSLocalizedString(@"Error") message: NSLocalizedString(@"You must enter an email address") delegate:nil cancelButtonTitle: NSLocalizedString(@"OK") otherButtonTitles:nil];
[messageBox show];

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Android

Use the AlertDialog to display error messages. As long as this is used, error messages and their associated functions will be accessible.

Android Pass Example

//Use an Android standard alert dialog to display error messages
AlertDialog.Builder builder = new AlertDialog.Builder(this);
 
builder.setMessage(//Error Message String)
builder.setCancelable(true);
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialog, int id) {
        dialog.cancel();
    }
});
AlertDialog alert = builder.create(); 
alert.show();

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HTML

A JavaScript alert is one option for HTML to meet this standard.

HTML Pass Example

<script>
    alert('Status message');
</script>

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Testing

Procedures

1. Activate a screen reader.
2. Trigger an alert or error on at the app level e.g.
   • Time out,
   • Update notice,
   • Error contacting the server,
   • Other app level errors or alerts.
3. Verify that the alerts or error notifications are announced by assistive technologies.

Outcome

The following check is true:

• The app uses operating system standard methods for providing app level or non-action triggered alerts and indicating errors to users which are announced by assistive technologies.

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