我有一个TableView内置TextField的自定义单元格，遗憾的是我得到了一个主题1：致命错误：在解包一个可选值时出乎意料地发现了nil我使用它们（按返回或触摸textField外面的屏幕以退出占位符）。
这是我的代码：
class WalletTableViewController: UIViewController, UITextFieldDelegate {
var cryptosArray: [Cryptos] = []
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
loadCryptoArray()
}
func loadCryptoArray() {
if UserDefaults.standard.object(forKey: "cryptosArray") != nil {
if let decoded = UserDefaults.standard.object(forKey: "cryptosArray") as? Data? {
let decodedCryptoArray = NSKeyedUnarchiver.unarchiveObject(with: decoded!) as! [Cryptos]
cryptosArray = decodedCryptoArray
}
}
}
}
TableView扩展程序：
extension WalletTableViewController: UITableViewDelegate, UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return cryptosArray.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let crypto = cryptosArray[indexPath.row]
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! WalletTableViewCell
cell.setCrypto(crypto: crypto)
cell.delegate = self
cell.amountTextField.delegate = self
return cell
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 85
}
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
if editingStyle == .delete {
cryptosArray.remove(at: indexPath.row)
tableView.deleteRows(at: [indexPath], with: .fade)
let userDefaults = UserDefaults.standard
let encodedData : Data = NSKeyedArchiver.archivedData(withRootObject: cryptosArray)
userDefaults.set(encodedData, forKey: "cryptosArray")
userDefaults.synchronize()
}
}
}
这是TextField：
extension WalletTableViewController: CryptoCellDelegate {
func cellAmountEntered(_ sender: Any) {
if WalletTableViewCell().amountTextField.text == "" {
return
}
let str = WalletTableViewCell().amountTextField.text
let formatter = NumberFormatter()
formatter.locale = Locale(identifier: "en_US")
let dNumber = formatter.number(from: str!)
let nDouble = dNumber!
let eNumber = Double(truncating: nDouble)
WalletTableViewCell().amountLabel.text = String(format:"%.8f", eNumber)
UserDefaults.standard.set(WalletTableViewCell().amountLabel.text, forKey: "bitcoinAmount")
WalletTableViewCell().amountTextField.text = ""
}
}
自定义单元格文件：
protocol CryptoCellDelegate {
func cellAmountEntered(_ sender: Any)
}
class WalletTableViewCell: UITableViewCell {
@IBOutlet weak var cryptoNameLabel: UILabel!
@IBOutlet weak var amountLabel: UILabel!
@IBOutlet weak var amountTextField: UITextField!
var cryptoItem: Crypto!
var delegate: CryptoCellDelegate?
func setCrypto(crypto: Cryptos) {
cryptoNameLabel.text = crypto.name
}
@IBAction func amountTextFieldEntered(_ sender: Any) {
delegate?.cellAmountEntered((Any).self)
}
}
TableView包含与用户想要的一样多的单元格，因此这取决于创建单元格的对象的array。
我想我某处有delegate问题？我对UITableView很陌生，所以这是一个相当大的挑战，请原谅任何愚蠢的错误：）
PS：我试图通过删除keyboard函数和不相关的东西来缩短代码，请告诉我你是否还需要其他东西。
答案 0 :(得分：1)
您使用WalletTableViewCell()的任何地方都在创建WalletTableViewCell的新实例。发生崩溃的原因是您以编程方式创建崩溃，而WalletTableViewCell是使用故事板设计的，并且由于您没有使用故事板对其进行实例化，因此@IBOutlet尚未设置，因此nil。CryptoCellDelegate。
<强>更新
尝试使用此方法修复它。将protocol CryptoCellDelegate {
func cellAmountEntered(_ walletTableViewCell: WalletTableViewCell)
}
更新为：
WalletTableViewCell然后在amountTextFieldEntered更新@IBAction func amountTextFieldEntered(_ sender: Any) {
delegate?.cellAmountEntered(self)
}
中：
extension WalletTableViewController: CryptoCellDelegate {
func cellAmountEntered(_ walletTableViewCell: WalletTableViewCell) {
// now you can use walletTableViewCell to access the cell that called the delegate method
if walletTableViewCell.amountTextField.text == "" {
return
}
let str = walletTableViewCell.amountTextField.text
let formatter = NumberFormatter()
formatter.locale = Locale(identifier: "en_US")
let dNumber = formatter.number(from: str!)
let nDouble = dNumber!
let eNumber = Double(truncating: nDouble)
walletTableViewCell.amountLabel.text = String(format:"%.8f", eNumber)
UserDefaults.standard.set(walletTableViewCell.amountLabel.text, forKey: "bitcoinAmount")
walletTableViewCell.amountTextField.text = ""
}
}
最后更新委托实施：
{"name":"a1", "std":"9", "year":"2017", "exam":"halfyr_T", "marks":[{"p":"45","m":"40","c":"50"}]}
{"name":"a1", "std":"9", "year":"2017", "exam":"halfyr_P", "marks":[{"p":"40","m":"28","c":"38"}]}
{"name":"a1", "std":"9", "year":"2017", "exam":"annual_T", "marks":[{"p":"40","m":"50","c":"48"}]}
{"name":"a1", "std":"9", "year":"2017", "exam":"annual_P", "marks":[{"p":"45","m":"42","c":"18"}]}
{"name":"a2", "std":"9", "year":"2017", "exam":"halfyr_T", "marks":[{"p":"25","m":"30","c":"50"}]}
{"name":"a2", "std":"9", "year":"2017", "exam":"halfyr_P", "marks":[{"p":"41","m":"48","c":"28"}]}
{"name":"a2", "std":"9", "year":"2017", "exam":"annual_T", "marks":[{"p":"30","m":"48","c":"24"}]}
{"name":"a2", "std":"9", "year":"2017", "exam":"annual_P", "marks":[{"p":"35","m":"08","c":"38"}]}
{"name":"b1", "std":"10", "year":"2017", "exam":"halfyr_T","marks":[{"p":"45","m":"40","c":"50"}]}
{"name":"b1", "std":"10", "year":"2017", "exam":"halfyr_P", "marks": [{"p":"40","m":"28","c":"38"}]}
{"name":"b1", "std":"10", "year":"2017", "exam":"annual_T", "marks": [{"p":"40","m":"50","c":"48"}]}
{"name":"b1", "std":"10", "year":"2017", "exam":"annual_P", "marks": [{"p":"45","m":"42","c":"18"}]}
{"name":"b2", "std":"10", "year":"2017", "exam":"halfyr_T", "marks": [{"p":"25","m":"30","c":"50"}]}
{"name":"b2", "std":"10", "year":"2017", "exam":"halfyr_P", "marks": [{"p":"41","m":"48","c":"28"}]}
{"name":"b2", "std":"10", "year":"2017", "exam":"annual_T", "marks": [{"p":"30","m":"48","c":"24"}]}
{"name":"b2", "std":"10", "year":"2017", "exam":"annual_P", "marks": [{"p":"35","m":"08","c":"38"}]}