[self addTitle:@"提示" mes:@"密码不能少于3位" aTitle:@"我知道了"];

-(void)addTitle:(NSString *)title mes:(NSString *)mes aTitle:(NSString *)aTitle

{

UIAlertController *actionController = [UIAlertController alertControllerWithTitle:title message:mes preferredStyle:UIAlertControllerStyleAlert ];

UIAlertAction *alertAction = [UIAlertAction actionWithTitle:aTitle style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {

}];

[actionController addAction:alertAction];

[self presentViewController:actionController animated:true completion:nil];

return;

}