ios - 如何使 UIScrollView 水平

Question

我正在使用一个 UIScrollView，我想在其中显示图像，但问题是我需要水平显示这些图像，现在它们只垂直显示，我怎样才能改变我的 UIScrollView 的方向，从垂直方向水平方向

这是我的类(class)，您在其中实现了 UIScrollView:

//

//  fastoClass.swift
//  AutoLayout(
//  Created by Barbatos on 5/14/18.
//  Copyright © 2018 Seccion 15. All rights reserved.
//
import UIKit

class fastoClass: UIViewController {

@IBOutlet weak var scrollHorizont: UIScrollView!

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

 override func viewDidAppear(_ animated: Bool) {

  var constraints = [NSLayoutConstraint]()
  var i = 0
  var previousLeft: UIView? = nil
  var previousRight: UIView? = nil

  let scrollWidth: CGFloat = self.scrollHorizont.frame.size.width / 2.0
  let imageColors = [UIColor.green, UIColor.lightGray, UIColor.blue, UIColor.red]

        for color in imageColors{
          let newImage = UIImageView()
          newImage.backgroundColor = color
          newImage.translatesAutoresizingMaskIntoConstraints = false
          var toView : UIView? = nil
          var toAttribute : NSLayoutAttribute?
          let isLeft = (i % 2) == 0
          if isLeft {

                toView = self.scrollHorizont

                toAttribute = NSLayoutAttribute.leading

            } else {

                toView = previousLeft

                toAttribute = NSLayoutAttribute.trailing

            }

            var topView : UIView? = nil

            var topAttribute : NSLayoutAttribute?

            if i < 2 {

                topView = self.scrollHorizont

                topAttribute = NSLayoutAttribute.top

            } else {

                if isLeft {

                    topView = previousLeft

                } else {

                    topView = previousRight

                }

                topAttribute = NSLayoutAttribute.bottom

            }

            let top = NSLayoutConstraint(item: newImage,

                                         attribute: NSLayoutAttribute.top,

                                         relatedBy: NSLayoutRelation.equal,

                                         toItem: topView,

                                         attribute: topAttribute!,

                                         multiplier: 1.0,

                                         constant: 0)

            let leading = NSLayoutConstraint(item: newImage,

                                             attribute: NSLayoutAttribute.leading,

                                             relatedBy: NSLayoutRelation.equal,

                                             toItem: toView,

                                             attribute: toAttribute!,

                                             multiplier: 1.0,

                                             constant: 0)

            let width = NSLayoutConstraint(item: newImage,

                                           attribute: NSLayoutAttribute.width,

                                           relatedBy: NSLayoutRelation.equal,

                                           toItem: self.scrollHorizont,

                                           attribute: NSLayoutAttribute.width,

                                           multiplier: 0.5,

                                           constant: 0)

            let height = NSLayoutConstraint(item: newImage,

                                            attribute: NSLayoutAttribute.height,

                                            relatedBy: NSLayoutRelation.equal,

                                            toItem: nil,

                                            attribute: NSLayoutAttribute.notAnAttribute,

                                            multiplier: 1.0,

                                            constant: scrollWidth)

            constraints.append(top)

            constraints.append(leading)

            constraints.append(width)

            constraints.append(height)



            self.scrollHorizont.addSubview(newImage)

            i += 1

            if isLeft {

                previousLeft = newImage

            } else {

                previousRight = newImage

            }

        }

        self.scrollHorizont.addConstraints(constraints)

        self.scrollHorizont.layoutSubviews()

        let contentHeight : CGFloat = scrollWidth * (CGFloat(i) / 2.0)

        self.scrollHorizont.contentSize = CGSize(width: self.scrollHorizont.frame.size.width, height: contentHeight)

    }

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()


    }

}

Answer 1

你可以试试这个

override func viewDidAppear(_ animated: Bool) {

    var constraints = [NSLayoutConstraint]()

    var i = 0

    var previousLeft: UIView? = nil

    let imageColors = [UIColor.green, UIColor.lightGray, UIColor.blue, UIColor.red]

    for color in imageColors{

        let newImage = UIImageView()

        newImage.backgroundColor = color

        newImage.translatesAutoresizingMaskIntoConstraints = false


        if previousLeft == nil {

            previousLeft = scrollHorizont

        }

        var con:NSLayoutAttribute? = nil

        if previousLeft == self.scrollHorizont {

            con = NSLayoutAttribute.leading

        }
        else {

            con = NSLayoutAttribute.trailing

        }

        self.scrollHorizont.addSubview(newImage)


        let top = NSLayoutConstraint(item: newImage,

                                     attribute: NSLayoutAttribute.top,

                                     relatedBy: NSLayoutRelation.equal,

                                     toItem: previousLeft,

                                     attribute: NSLayoutAttribute.top,

                                     multiplier: 1.0,

                                     constant: 0)

        let leading = NSLayoutConstraint(item: newImage,

                                         attribute: NSLayoutAttribute.leading,

                                         relatedBy: NSLayoutRelation.equal,

                                         toItem: previousLeft,

                                         attribute: con!,

                                         multiplier: 1.0,

                                         constant: 0)

        let width = NSLayoutConstraint(item: newImage,

                                       attribute: NSLayoutAttribute.width,

                                       relatedBy: NSLayoutRelation.equal,

                                       toItem: self.scrollHorizont,

                                       attribute: NSLayoutAttribute.width,

                                       multiplier: 1,

                                       constant: 0)

        let height = NSLayoutConstraint(item: newImage,

                                        attribute: NSLayoutAttribute.height,

                                        relatedBy: NSLayoutRelation.equal,

                                        toItem: self.scrollHorizont,

                                        attribute: NSLayoutAttribute.height,

                                        multiplier: 1.0,

                                        constant: 0)



        if i == imageColors.count - 1 {

            let tra = NSLayoutConstraint(item: newImage,

                                            attribute: NSLayoutAttribute.trailing,

                                            relatedBy: NSLayoutRelation.equal,

                                            toItem: self.scrollHorizont,

                                            attribute: NSLayoutAttribute.trailing,

                                            multiplier: 1.0,

                                            constant: 0)

            constraints.append(tra)


        }


        constraints.append(top)

        constraints.append(leading)

        constraints.append(width)

        constraints.append(height)

        previousLeft = newImage

        i += 1


    }

    self.scrollHorizont.addConstraints(constraints)

}