Max Width for alertview?

In my iPad i am using alertview, my problem is when i am tr开发者_JS百科ying to increase the width of alertview it was not increasing. Any Max width is there for alertview. As i am beginner for this. can anybody help me. i used the like below

- (void)willPresentAlertView:(UIAlertView *)alertView {
    if ( alertView.tag==1 ) //MP: This tag differentiates between many alert views..so crazy :)
    {
        CGRect alertFrame = CGRectMake(250.0, 400.0, 650.0, 150.0);
        alertView.frame = alertFrame;
    }
}

UIAlertView doesn't support custom width setting.

Here is a UIAlertView-replacement class that does support custom width:

https://github.com/TomSwift/TSAlertView