如何从Swift中的另一个视图调用contentOffset？

Question

class oneViewController: UIViewController{
   let sv = UIScrollView();
   override func viewDidLoad() {
   super.viewDidLoad();

   sv.frame = CGRectMake(0, 100, screenWidth, screenHeight);
   sv.backgroundColor = UIColor.clearColor();
   sv.contentSize = CGSize(width: sv.frame.size.width*3 ,height: sv.frame.size.height);
   sv.delegate = self;
   scrollToContentOffsetX(screenWidth);
   self.view.addSubview(sv);
   }


  func scrollToContentOffsetX(offsetX:CGFloat) {

       sv.contentOffset.x = offsetX;
  }
}

I can scroll UIScrollView,it working.But I call from another View,its not working.

class anthorView: UIView{

    override init (frame : CGRect)
    {

    super.init(frame : frame)

      let btnForget = UIButton(frame: CGRectMake(screenWidth-155, txtPWD.frame.origin.y+txtPWD.frame.size.height+5, 70, 30));
      btnForget.setTitle("Forget", forState: UIControlState.Normal);
      btnForget.setTitleColor(UIColor.blackColor(), forState: UIControlState.Normal);
      btnForget.addTarget(self, action: #selector(btnForget_Click), forControlEvents: .TouchUpInside);
      btnForget.titleLabel!.font = UIFont.systemFontOfSize(14);
      btnForget.backgroundColor = UIColor.clearColor();
      self.addSubview(btnForget);
    }

func btnForget_Click(sender: AnyObject) {

    oneViewController().scrollToContentOffsetX(0);

  }
} 

I have breakpoint,both have go func scrollToContentOffsetX(offsetX:CGFloat). who can help me and sry for my English

Answer 1

Problem in your code pointed by @AminNegm-Awad: in btnForget_Click you create completely new instance of oneViewController , which will never appear on screen and have no connection to existed oneViewController . You need to have pointer to your existed instance of oneViewController in your anthorView instance. Usual way for view to "talk" with controller is protocol-delegate. Read about it by yourself; here I will offer another solution with closure. Anyway, you will need to have pointer to your anthorView instance (lets declare it as anthorViewInstance property) in oneViewController . Here is changes that you need add to your classes

class anthorView:

var offsetClosure: (CGFloat -> ())?

func btnForget_Click(sender: AnyObject) {
    // delete previous implementation
    offsetClosure?(0)
}

class oneViewController:

var anthorViewInstance: anthorView!

override func viewDidLoad() {
    super.viewDidLoad()

    // some your code...

    // next line is initialization of anthorView, do it in other place if you wish
    anthorViewInstance = anthorView(frame: CGRectZero)
    anthorViewInstance.offsetClosure = 
        {
             [weak self]
             offsetX in
             self?.scrollToContentOffsetX(offsetX)
        }    
}

---

Also, there is local case for this solution can be performed in your case. You may set button action of anthorView directly from view controller. For do this declare button as property in anthorView

class anthorView:

var btnForget: UIButton!

super.init(frame : frame) {
    btnForget = UIButton(frame: CGRectMake(screenWidth-155, txtPWD.frame.origin.y+txtPWD.frame.size.height+5, 70, 30))

    // ... other init code

    // remove btnForget.addTarget line
}

// move btnForget_Click method to view controller

class oneViewController:

var anthorViewInstance: anthorView!

override func viewDidLoad() {
    super.viewDidLoad()

    // some your code...

    // next line is initialization of anthorView, do it in other place if you wish
    anthorViewInstance = anthorView(frame: CGRectZero)
    anthorViewInstance.btnForget.addTarget(self, action: #selector(btnForget_Click), forControlEvents: .TouchUpInside)  
}

func btnForget_Click() {
    scrollToContentOffsetX(0)
}