json - 我无法从数据库加载数据来显示 UIPickerView 的结果

Question

我无法从数据库加载数据来显示 UIPickerView 的结果。我通过修复数组值进行测试 UIPicker 可以将数据加载到 pickerView 但当我使用数组加载 json UIPickerViewDataSource 无法加载到选取器 View

可以加载

var team = ["Apple", "Banana", "Tomato", "Corn", "Bean", "Orange", "Mango", "Mangoteen"]

无法加载

var team: [AnyObject] = []

import UIKit

class getAllTeamViewController: UIViewController,UIPickerViewDataSource,UIPickerViewDelegate, UITextFieldDelegate {

var selectValue: String?

@IBOutlet weak var showSelectValuePickerView: UITextField!

// Array
    //var team = ["Apple", "Banana", "Tomato", "Corn", "Bean", "Orange", "Mango", "Mangoteen"]
    var team: [AnyObject] = []

//Function getValue from database
func getvalue() -> Void {
    //get the values from sql/Json
    let url = NSURL(string: "http://www.test.com/myWebService/getteamPickView.php")

    let data = NSData(contentsOf: url! as URL)
    var jsonResponse = try! JSONSerialization.jsonObject(with: data! as Data, options: JSONSerialization.ReadingOptions.mutableContainers) as! NSArray
        jsonResponse = jsonResponse.reversed() as NSArray
        reloadInputViews()
        print("jsonResponse ==> \(jsonResponse)")

    for candidate in jsonResponse {
        if let cdict = candidate as? NSDictionary {
            //fullName is the column name in sql/json
            let names = cdict["NameTeam"]
            self.selectValue?.append(((names! as AnyObject) as! String))
            print("Names ==> \(String(describing: names))")
        }//if
    }//for
}//getvalue

//  Picker View Function
func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
}

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return self.team.count
}

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    let titleRow = (team[row] )
    return titleRow as? String
}

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {

    if team.count > 0 && team.count >= row{
        self.showSelectValuePickerView.text = self.team[row] as? String 
        self.showSelectValuePickerView.isHidden = true
    }
}

}

Answer 1

抱歉，这是非常糟糕的代码。有很多不好的做法。

• 如果数组明显是 [String]，请勿将其声明为 [AnyObject]。
  这避免了像名称这样可怕的类型转换!作为 AnyObject)作为!字符串
• 不要在 Swift 中使用 NSData、NSURL、NSArray、NSDictionary。使用原生类型。
• .mutableContainers 在 Swift 中没有意义，省略整个参数。
• 从不使用 Data(contentsOf) 从远程 URL 同步加载数据。
• 始终在主线程上重新加载 UI。
• 处理所有错误!至少打印它们。

发生错误的原因是您在填充数据源数组之前调用了 reloadInputViews()(我假设它会重新加载选取器 View )。

并且不是填充数据源数组team，而是将字符串附加到selectValue，这是没有意义的。

这是代码的稍微优化版本

@IBOutlet weak var showSelectValuePickerView: UITextField!

var team = [String]()

//Function getValue from database
func getvalue() {
    //get the values from sql/Json
    let url = URL(string: "http://www.test.com/myWebService/getteamPickView.php")!
    let task = URLSession.shared.dataTask(with: url) { (data, _ , error) in
        if let error = error { print(error); return }
        do {
            if let jsonResponse = try JSONSerialization.jsonObject(with: data!) as? [[String:Any]] {
                self.team = jsonResponse.compactMap{ $0["NameTeam"] as? String }
                DispatchQueue.main.async {
                    self.reloadInputViews()
                }
            } else { print("JSON is not an array") }
        } catch { print(error) }
    }
    task.resume()
}

//  Picker View Function
func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
}

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return self.team.count
}

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    return team[row]
}

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    self.showSelectValuePickerView.text = self.team[row]
    self.showSelectValuePickerView.isHidden = true // Are you serious ??? This hides the text field
}