为什么这个stackview不能在游乐场工作？

Question

有什么想法吗？

    import UIKit
    import PlaygroundSupport

    extension CGRect {
        init(_ x:CGFloat, _ y:CGFloat, _ w:CGFloat, _ h:CGFloat) {
            self.init(x:x, y:y, width:w, height:h)
        }
    }

    let v0 = UIView(frame: CGRect(0, 0, 500, 500))
    v0.backgroundColor = .white

    let v1 = UIView(frame: CGRect(0,0,500,100))
    v1.backgroundColor = .red
    v1.translatesAutoresizingMaskIntoConstraints = false

    let v2 = UIView(frame: CGRect(0,200,500,100))
    v2.backgroundColor = .yellow
    v2.translatesAutoresizingMaskIntoConstraints = false

    let v3 = UIView(frame: CGRect(0,400,500,100))
    v3.backgroundColor = .blue
    v3.translatesAutoresizingMaskIntoConstraints = false

    let sv = UIStackView(frame: CGRect(0, 0, 500, 500))
    sv.addArrangedSubview(v1)
    sv.addArrangedSubview(v2)
    sv.addArrangedSubview(v3)
    sv.axis = .vertical
    sv.alignment = .center
    sv.distribution = .fillEqually
    sv.translatesAutoresizingMaskIntoConstraints = false
    sv.backgroundColor = .orange

    v0.addSubview(sv)

NSLayoutConstraint.activate([

sv.topAnchor.constraint(equalTo: v0.topAnchor),
    sv.leadingAnchor.constraint(equalTo: v0.leadingAnchor),
    sv.trailingAnchor.constraint(equalTo: v0.trailingAnchor),
        sv.bottomAnchor.constraint(equalTo: v0.bottomAnchor),
    ])

    PlaygroundPage.current.liveView = v0

这就是我所看到的......

Answer 1

在相反的轴上，它需要对大小进行约束。

因此，当stackview处于垂直模式时，我添加了这些约束......

let parameters = ["part":"snippet","maxResults":50,"channelId":CHANNEL_ID,"playlistId":UPLOADS_PLAYLIST_ID,"key":API_KEY] as [String : Any]

class VideoModel: NSObject {

    var videoArray = [Video]()


    func getFeedVideo() {
        Alamofire.request("https://www.googleapis.com/youtube/v3/playlistItems", parameters: parameters, encoding: URLEncoding.default, headers: nil).responseJSON { (response) in

            if let JSON = response.result.value {

                if let dictionary = JSON as? [String: Any] {

                    var arrayOfVideos = [Video]()

                    guard let items = dictionary["items"] as? NSArray else { return }

                    for items in dictionary["items"] as! NSArray {
                        print(items)
                        //  Create video objects off of the JSON response

                        let videoObj = Video()
                        videoObj.videoID = (items as AnyObject).value(forKeyPath: "snippet.resourceId.videoId") as! String
                        videoObj.videoTitle = (items as AnyObject).value(forKeyPath: "snippet.title") as! String
                        videoObj.videoDescription = (items as AnyObject).value(forKeyPath: "snippet.description") as! String
                        videoObj.videoThumbnailUrl = (items as AnyObject).value(forKeyPath: "snippet.thumbnails.maxres.url") as! String


                        arrayOfVideos.append(videoObj)

                    }
                    self.videoArray = arrayOfVideos
                    if self.delegate != nil {
                        self.delegate!.dataReady()
                    }
                }
            }
        }
    }

横向......

v1.widthAnchor.constraint(equalTo: v0.widthAnchor)
v2.widthAnchor.constraint(equalTo: v0.widthAnchor)
v3.widthAnchor.constraint(equalTo: v0.widthAnchor)

还可以删除彩色视图上的帧。