UIAlertController 文案居左，左对齐

如题， UIAlertController 的文案居左显示，左对齐。代码如下

UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"温馨提示" message:@"温馨提示比较长" preferredStyle:UIAlertControllerStyleAlert];
    UIAlertAction *actionC = [UIAlertAction actionWithTitle:@"已确定并知悉该事项" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        [[NSUserDefaults standardUserDefaults] setValue:@"hadshow" forKey:@"showNotSupportFastRedeem"];
    }];
    // 设置左对齐
    ///设置左对齐
//    UILabel *label1 = [alertVC.view valueForKeyPath:@"_titleLabel"];
    UILabel *label2 = [alertController.view valueForKeyPath:@"_messageLabel"];
    if (label2) {
//    label1.textAlignment = NSTextAlignmentLeft;
        label2.textAlignment = NSTextAlignmentLeft;
    }
    
    [alertController addAction:actionC];
    [self presentViewController:alertController animated:YES completion:nil];