設定標簽為CoreData中的字串

我正在嘗試將 UILabel.text 設定為一個位于 coredata 中的字串，但是我收到一個錯誤訊息：有Instance member "test1" cannot be used on type 'ProfileViewController' did you mean to use a value of this type instead?什么解決方案嗎？

    override func viewWillAppear(_ animated: Bool) {
        let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Users")
                request.returnsObjectsAsFaults = false
                do {
                    let result = try context.fetch(request)
                    for data in result as! [NSManagedObject] {
                        test1 = data.value(forKey: "username") as! String
                  }
                } catch {
                    print("Failed")
                }
    }
    var test1 = String()
    let nameLabel: UILabel = {
        let label = UILabel()
        label.textAlignment = .center
        label.text = test1  //error is here
        label.font = UIFont.boldSystemFont(ofSize: 26)
        label.textColor = .white
        return label
    }()

uj5u.com熱心網友回復：

test1創建標簽時不需要參考。a 的text屬性UILabel是一個可選字串，因此不賦值是完全合法的。

即使你可以/確實分配了test1，它也不會幫助你實作你想要的，因為UIKit它不適用于系結；為test1in分配新值viewDidAppear不會更改標簽中的值。

您還需要將您nameLabel的添加到視圖控制器view并設定一些約束或設定其frame; 我假設您已經完成了此操作，viewDidLoad但未在此處顯示。

所有你需要的是：

let nameLabel: UILabel = {
    let label = UILabel()
    label.textAlignment = .center
    label.font = UIFont.boldSystemFont(ofSize: 26)
    label.textColor = .white
    return label
}()

override func viewWillAppear(_ animated: Bool) {
    let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Users")
    request.returnsObjectsAsFaults = false
    do {
        let result = try context.fetch(request) 
        if let result = result as? [NSManagedObject] {
        for data in result {
            self.nameLabel.text = data.value(forKey:"username") as? String
        }
    } catch {
        print("Failed")
    }

    super.viewDidAppear(animated) // Don't forget to call super
}

如果您確實想將名稱保留在屬性中，那么您可以使用didSet函式實作偽系結：

let nameLabel: UILabel = {
    let label = UILabel()
    label.textAlignment = .center
    label.font = UIFont.boldSystemFont(ofSize: 26)
    label.textColor = .white
    return label
}()

var name: String? {
    didSet {
        self.nameLabel.text = name
    }
}

override func viewWillAppear(_ animated: Bool) {
    let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Users")
    request.returnsObjectsAsFaults = false
    do {
        let result = try context.fetch(request) 
        if let result = result as? [NSManagedObject] {
        for data in result {
            self.name = data.value(forKey:"username") as? String
        }
    } catch {
        print("Failed")
    }

    super.viewDidAppear(animated) // Don't forget to call super
}

uj5u.com熱心網友回復：

嘗試這個：

override func viewDidAppear() {
    super.viewDidLoad()
    test()                                 // run the func here 
}


func test() {
    var test1 = String()
    let nameLabel: UILabel = {
        let label = UILabel()
        label.textAlignment = .center
        label.text = test1  //error is here
        label.font = UIFont.boldSystemFont(ofSize: 26)
        label.textColor = .white
        return label
    }()
}

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