Why page view don't work : I have an uiviewcontroller with a tabliew. Then I create a pageview containt two viewcontroller. Pageview don't work if I pass data to child. If I change

    setViewControllers([subjective], direction: .Forward, animated: true, completion: nil)
 
to  

    setViewControllers([firstVC], direction: .Forward, animated: true, completion: nil)

Pageview work but data don't pass. I don't have any idea about it. Help me please. Thanks

This is my pageview:

    import UIKit

    class PageVC : UIPageViewController, UIPageViewControllerDelegate, UIPageViewControllerDataSource {
    
    var lblhoten = String()
    var lblngaysinh = String()
    var lblsodt = String()
    
    lazy var VCArr: [UIViewController] = {
        return [self.VCInstance("ThongTinBNPage2"),
                self.VCInstance("ThongTinBNPage3")]
    }()
    
    private func VCInstance(name: String) -> UIViewController {
        return UIStoryboard(name: "Main", bundle: nil).instantiateViewControllerWithIdentifier(name)
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.dataSource = self
        self.delegate = self
        if let firstVC = VCArr.first {
            let subjective = self.storyboard?.instantiateViewControllerWithIdentifier("ThongTinBNPage2") as! VCSubjective
            subjective.lblhoten = lblhoten
            subjective.lblngaysinh = lblngaysinh
            subjective.lblsodt = lblsodt
            setViewControllers([subjective], direction: .Forward, animated: true, completion: nil)
        }
    }
    
    public func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
        guard let viewcontrollerindex = VCArr.indexOf(viewController) else {
            return nil
        }
        
        let previousindex = viewcontrollerindex - 1
        
        
        guard previousindex >= 0 else {
            return VCArr.last
        }
        
        guard VCArr.count > previousindex else {
            return nil
        }
        
        return VCArr[previousindex]
    }
    
    public func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
        guard let viewcontrollerindex = VCArr.indexOf(viewController) else {
            return nil
        }
        
        let nextindex = viewcontrollerindex + 1
        
        
        guard nextindex < VCArr.count else {
            return VCArr.first
        }
        
        guard VCArr.count > nextindex else {
            return nil
        }
        
        return VCArr[nextindex]
    }
    
    public func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int {
        return VCArr.count
    }
    
    // The selected item reflected in the page indicator.
    public func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int {
        guard let firstviewcontroller = viewControllers?.first,
            let firstviewcontrollerindex = VCArr.indexOf(firstviewcontroller) else {
                return 0
        }
        
        return firstviewcontrollerindex
    }
}


