使用我确保[alertView show];正在调用的调试器,但对话框不可见,我还需要做什么才能显示它?
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo
{
    if( [[userInfo objectForKey:@"aps"] objectForKey:@"alert"] != NULL)
    {
        NSString *msg = [[userInfo objectForKey:@"aps"] objectForKey:@"alert"];
        if(msg != nil) {
            UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Usage Alert"
            message:msg  delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Ok", nil];
            [alertView show];
        }
    }
}