Question

嗨，我正在通过尝试创作来学习。我有一个我正在使用的演示代码，想要知道是否有一种方法可以改变它显示的图像（硬写入）（汽车的名称）并更改它，以便它显示来自网址的图像。因为我正在尝试学习这些东西，并且可以获得如何为其他事情做这些事情的例子，但似乎很难将其纳入此代码。我希望你能提供帮助。

我有一个课程调用Post，我从firebase获取图像。所以我使用：post.imageUrl1作为图片网址。

class DemoViewController: ExpandingViewController {
@IBAction func backPressed(_ sender: Any) {
}

   var post: Post!

 typealias ItemInfo = (imageName: String, title: String)
fileprivate var cellsIsOpen = [Bool]()
fileprivate let items: [ItemInfo] = [("Ferrari", "Ferrari"),("Bug",  "Bugatti"),("car", "Mustang"),("BM", "BMW")]

@IBOutlet weak var pageLabel: UILabel!
@IBOutlet weak var titleImageView: UIImageView!
@IBOutlet weak var titleImageViewXConstraint: NSLayoutConstraint!

}

// MARK: - Lifecycle 
extension DemoViewController {



override func viewDidLoad() {
itemSize = CGSize(width: 256, height: 335)
super.viewDidLoad()




registerCell()
fillCellIsOpenArray()
addGesture(to: collectionView!)
configureNavBar()
 }

override func viewWillLayoutSubviews() {
super.viewWillLayoutSubviews()
guard let titleView = navigationItem.titleView else { return }
let center = UIScreen.main.bounds.midX
let diff = center - titleView.frame.midX
titleImageViewXConstraint.constant = diff
}


}

// MARK: Helpers
extension DemoViewController {

 fileprivate func registerCell() {

   let nib = UINib(nibName: String(describing:       DemoCollectionViewCell.self), bundle: nil)
collectionView?.register(nib, forCellWithReuseIdentifier:  String(describing: DemoCollectionViewCell.self))
  }

  fileprivate func fillCellIsOpenArray() {
  cellsIsOpen = Array(repeating: false, count: items.count)
   }

fileprivate func getViewController() -> ExpandingTableViewController {
let storyboard = UIStoryboard(storyboard: .Main)
let toViewController: DemoTableViewController = storyboard.instantiateViewController()
return toViewController
}

fileprivate func configureNavBar() {
navigationItem.leftBarButtonItem?.image =  navigationItem.leftBarButtonItem?.image!.withRenderingMode(UIImageRenderingMode.alwaysOriginal)
 }

 }

/// MARK: Gesture
extension DemoViewController {

fileprivate func addGesture(to view: UIView) {
let upGesture = Init(UISwipeGestureRecognizer(target: self, action: #selector(DemoViewController.swipeHandler(_:)))) {
  $0.direction = .up
 }

 let downGesture = Init(UISwipeGestureRecognizer(target: self, action: #selector(DemoViewController.swipeHandler(_:)))) {
  $0.direction = .down
 }
view.addGestureRecognizer(upGesture)
view.addGestureRecognizer(downGesture)
}

func swipeHandler(_ sender: UISwipeGestureRecognizer) {
let indexPath = IndexPath(row: currentIndex, section: 0)
guard let cell  = collectionView?.cellForItem(at: indexPath) as?  DemoCollectionViewCell else { return }
// double swipe Up transition
if cell.isOpened == true && sender.direction == .up {
  pushToViewController(getViewController())

  if let rightButton = navigationItem.rightBarButtonItem as?  AnimatingBarButton {
    rightButton.animationSelected(true)
   }
   }

  let open = sender.direction == .up ? true : false
  cell.cellIsOpen(open)
  cellsIsOpen[indexPath.row] = cell.isOpened
  }

  }

// MARK: UIScrollViewDelegate
extension DemoViewController {

 func scrollViewDidScroll(_ scrollView: UIScrollView) {
 pageLabel.text = "\(currentIndex+1)/\(items.count)"
}

}

// MARK: UICollectionViewDataSource
extension DemoViewController {



 override func collectionView(_ collectionView: UICollectionView,   willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
super.collectionView(collectionView, willDisplay: cell, forItemAt: indexPath)
guard let cell = cell as? DemoCollectionViewCell else { return }

let index = indexPath.row % items.count
let info = items[index]
cell.backgroundImageView?.image = UIImage(named: info.imageName)
cell.customTitle.text = info.title
cell.cellIsOpen(cellsIsOpen[index], animated: false)
}

 func collectionView(_ collectionView: UICollectionView,  didSelectItemAtIndexPath indexPath: IndexPath) {
guard let cell = collectionView.cellForItem(at: indexPath) as? DemoCollectionViewCell
      , currentIndex == indexPath.row else { return }

if cell.isOpened == false {
  cell.cellIsOpen(true)
} else {
  pushToViewController(getViewController())

  if let rightButton = navigationItem.rightBarButtonItem as? AnimatingBarButton {
    rightButton.animationSelected(true)
   }
  }
 }

}

// MARK: UICollectionViewDataSource
extension DemoViewController {

override func collectionView(_ collectionView: UICollectionView,  numberOfItemsInSection section: Int) -> Int {
 return items.count
}

 override func collectionView(_ collectionView: UICollectionView,   cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
 return collectionView.dequeueReusableCell(withReuseIdentifier:  String(describing: DemoCollectionViewCell.self), for: indexPath)

  }

 }

Answer 1

您可以使用数据的指定构造函数从网址下载图片：let imageData = Data(contentsOf: "exampleURL.com")

然后您只需在Collection View数据源方法中使用它：

override func collectionView(_ collectionView: UICollectionView,   willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
    super.collectionView(collectionView, willDisplay: cell, forItemAt: indexPath)
    guard let cell = cell as? DemoCollectionViewCell else { return }

    let index = indexPath.row % items.count
    let info = items[index]
    //here I assumed you would create a .url property of ItemInfo, but you can access the URL any way you want to
    guard let imageUrl = URL(string: info.url) else { return }
    do {
        let imageData = try Data(contentsOf: imageUrl)
    } catch {
        //handle error here
    }
    cell.backgroundImageView?.image = UIImage(data: imageData)
    cell.customTitle.text = info.title
    cell.cellIsOpen(cellsIsOpen[index], animated: false)
}

从互联网上获取图像到一个集合中

1 个答案: