ScrollView does not scroll in iOS

Question

I want to allow users to scroll left or right but only one screen far.

//
//  MainViewController.swift
//  Calendar
//
//  Created by Andy on 7/22/17.
//  Copyright © 2017 Andy. All rights reserved.
//

import UIKit

class MainViewController: UIViewController, UIScrollViewDelegate {


    @IBOutlet weak var ScrollView: UIScrollView!{
        didSet{
            ScrollView.delegate = self
            ScrollView.contentSize = CGSize(width: ScrollView.frame.width * 3, height: ScrollView.frame.height)
        }
    }

    @IBOutlet weak var center: UIView!
    @IBOutlet weak var left: UIView!
    @IBOutlet weak var right: UIView!


    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }



    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if let destination = segue.destination as? ReusableViewController {
            if let identifier = segue.identifier{
                destination.currentYearOffSet = 0
                destination.currentMonthOffSet = 0
                switch identifier {
                case "center":
                    destination.position = .center
                case "left":
                    destination.position = .left
                case "right":
                    destination.position = .right
                default:
                    fatalError("Unexpected Segue Identifier")
                }
            }
        }
    }
}

This Controller does nothing more than getting the scroll work. And inside the scrollview there are three containerViews managed by other controllers. But that simply does not work.

I have done the following to solve the problem but in vain: 1. Check the content size of scrollView. 2. Hook up the controller and the three containerViews. 3. Set the scrollView delegate but I haven't implemented any method.(Maybe that's the cause but I don't know what to implement)

Plus, do I need to hook up those three containerViews when the controller does nothing about them?

EDIT: I removed: 1. contentSize 2. UIScrollViewDelegate 3. outlets of the three containerViews. This does make my code a lot more nicer, but scrollView still cannot scroll.

EDIT2: I add a view which is exactly the size I want scrollView.contentSize to be as the scrollView's immediate subview. And it seem that the content height is solved because it's only saying that the content width is ambiguous. It want to to add leading and trailing constraints to the view I added but I want it to just center horizontally in the scrollView. Now I need to set the leading and trailing constraints to let autoLayout know the contentWidth. How can I set the leading and trailing offSet based on the width of its superview or I'm supposed to do something else to solve this problem?

Hussain Shabbir Hussain Shabbir · Accepted Answer · 2017-07-30T23:16:47

You do not need to set like this:-

@IBOutlet weak var ScrollView: UIScrollView!{
        didSet{
            ScrollView.delegate = self
            ScrollView.contentSize = CGSize(width: ScrollView.frame.width * 3, height: ScrollView.frame.height)
        }
    }

Just having outlet @IBOutlet weak var ScrollView: UIScrollView! and pinning proper constraint(leading, trailing, top, bottom, equal Width(should be equal to or greater than to), equal height (should be equal to or greater than to).

For Horizontal scroll If you wanted to scrolling horizontally then also pinned width constraint, this is required to avoid auto layout error but inside placeholder checked Remove at build time.

For Vertical scroll If you wanted to scrolling vertically then also pinned height constraint, this is required to avoid auto layout error but inside placeholder checked Remove at build time.

Note:- You can use either both or any one based on your requirement.

ScrollView does not scroll in iOS

1 Answers