在公共类里面写如下两个类方法就可以了，只需要把第一个类方法公布出来：
代码如下：
#pragma mark --- 定时弹窗 ---
+ (void)showAlertViewWithTitle:(NSString *)title message:(NSString *)message afterDelay:(NSTimeInterval)delay {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:title message:message delegate:nil cancelButtonTitle:nil otherButtonTitles:nil];
[alert show];
[self performSelector:@selector(dimissAlert:) withObject:alert afterDelay:delay];
}
+ (void)dimissAlert:(UIAlertView *)alert {
if(alert) {
[alert dismissWithClickedButtonIndex:[alert cancelButtonIndex] animated:YES];
}
}