一，效果图。

二，代码。

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UIAlertView * alterView = [[UIAlertView alloc]initWithTitle:@"提示" message:@"以清除缓存" delegate:self cancelButtonTitle:nil otherButtonTitles:@"确认", nil];
    [alterView show];

}