将数据传递给 collectionViewCell

Question

我想在我的集合视图单元格中使用一些自定义结构。我从我的 API 服务获取数据并尝试将其传递到我的自定义集合视图单元格。

我找到了几个答案，但我仍然不知道该怎么做

这是我获得实际数据的地方：

    func FetchFormData(linkUrl: String) {

    let parameters: [String: AnyObject] = [:]

    let postString = (parameters.flatMap({ (key, value) -> String in
        return "\(key)=\(value)"
    }) as Array).joined(separator: "&")


    let url = URL(string: linkUrl)!
    var request = URLRequest(url: url)
    request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
    request.httpMethod = "POST"
    request.httpBody = postString.data(using: .utf8)
    let task = URLSession.shared.dataTask(with: request) { data, response, error in
        guard let data = data, error == nil else {
            print("error=\(String(describing: error))")
            return
        }

        if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode != 200 {
            print("statusCode should be 200, but is \(httpStatus.statusCode)")
            print("response = \(String(describing: response))")
        }

        let responseString = String(data: data, encoding: .utf8)

        let contentData = responseString?.data(using: .utf8)
        do {
            let decoder = JSONDecoder()
            self.formData = try decoder.decode(FormModel.self, from: contentData!)

        } catch let err {
            print("Err", err)
        }

        DispatchQueue.main.async {
            //here is the where I reload Collection View
            self.collectionView.reloadData()
        }

    }
    task.resume()
}

我也在此处尝试将数据传递给单元格：

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! BaseFormCollectionViewCell

    cell.backgroundColor = .green

    //Data could be print out here
    print(self.formData?.components?[indexPath.row])
    cell.formComponent = (self.formData?.components?[indexPath.row])!

    return cell
}

真正的问题是进入我的手机class

class BaseFormCollectionViewCell: UICollectionViewCell {

var formComponent: FormComponent!{
    didSet {
        //data can be print out here
        print("Passed value is: \(formComponent)")
    }
}

override init(frame: CGRect) {
    super.init(frame: frame)

    //this part is always nill
    print(formComponent)

}

}

正如你们在代码中看到的那样，在我的集合视图单元之前一切顺利。它应该简单得多，但我无法弄清楚发生了什么以及为什么会发生。

Answer 1

将您的单元格class修改为

class BaseFormCollectionViewCell: UICollectionViewCell {

var formComponent: FormComponent!{
    didSet {
        //this is unnecessary. You can achieve what u want with a bit more cleaner way using configure function as shown below 
        //data can be print out here
        print("Passed value is: \(formComponent)")
    }
 }

 override init(frame: CGRect) {
    super.init(frame: frame)

    //this part is always nill
    print(formComponent)

 }

 func configure() {
    //configure your UI of cell using self.formComponent here
 }
}

终于

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! BaseFormCollectionViewCell

    cell.backgroundColor = .green

    //Data could be print out here
    print(self.formData?.components?[indexPath.row])
    cell.formComponent = (self.formData?.components?[indexPath.row])!
    (cell as! BaseFormCollectionViewCell).configure()
    return cell
}

在 cellForItemAt 中查找 (cell as! BaseFormCollectionViewCell).configure() 这就是你如何在将数据传递到单元格上方的语句后触发单元格的 UI 配置。

坦率地说，您可以摆脱 didSet 并继续 configure，如图所示

希望对您有所帮助

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