UIAlertController提示消息设置左对齐

    UIAlertController *alertVC = [UIAlertController alertControllerWithTitle:@"提示" message:msg preferredStyle:(UIAlertControllerStyleAlert)];
    UIAlertAction *cancel = [UIAlertAction actionWithTitle:@"我知道了" style:(UIAlertActionStyleCancel) handler:^(UIAlertAction * _Nonnull action) {
        
    }];
    ///设置左对齐
    UILabel *label1 = [alertVC.view valueForKeyPath:@"_titleLabel"];
    UILabel *label2 = [alertVC.view valueForKeyPath:@"_messageLabel"];
    label1.textAlignment = NSTextAlignmentLeft;
    label2.textAlignment = NSTextAlignmentLeft;

    [alertVC addAction:cancel];
    [self presentViewController:alertVC animated:YES completion:nil];