Swift PickerView不顯示任何內容，沒有任何操作沒有列表

Question

我是一個快捷方式的新手。我相信我錯過了一些非常基本的東西。我試圖在我看來初始化一個PickerView，由於某種原因列表不顯示。當我點擊選取器時也沒有任何反應。我錯過了什麼？

奇怪的是，爲什麼不PickerView's有ID's像Label或TextView

這裏是視圖控制器代碼

class ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate { 

    var pickerView = UIPickerView() 
    var pickerDataSource = ["White", "Red", "Green", "Blue"]; 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     // Initialization for Country Code pickerView 
     pickerView.dataSource = self 
     pickerView.delegate = self 
     pickerView.isHidden = false 
    } 

    override func didReceiveMemoryWarning() { 
     super.didReceiveMemoryWarning() 
     // Dispose of any resources that can be recreated. 
    } 

    // Methods for Country Code pickerView 
    func numberOfComponents(in pickerView: UIPickerView) -> Int { 
     return 1 
    } 

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

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

編輯

我意識到，我沒有IBOutlet。要添加它，我遵循下面的說明。但是，現在如果我拖動並嘗試放入我的Viewcontroller彈出窗口不顯示。

另外，我手動添加了這一行，但它仍然不起作用。

@IBOutlet weak var picker: UIPickerView! 

EDIT 2

我試圖拖出口下降到ViewController。出於某種原因，我現在越來越Exception

檢查以下右上方圖片，你會發現delegate和「datasource`到視圖。這個可以嗎 ？

** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIView numberOfComponentsInPickerView:]: unrecognized selector sent to instance 0x7faa3a40a900' 
*** First throw call stack: 
(
    0 CoreFoundation      0x000000010dce8d4b __exceptionPreprocess + 171 
    1 libobjc.A.dylib      0x000000010d74a21e objc_exception_throw + 48 
    2 CoreFoundation      0x000000010dd58f04 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132 
    3 CoreFoundation      0x000000010dc6e005 ___forwarding___ + 1013 
    4 CoreFoundation      0x000000010dc6db88 _CF_forwarding_prep_0 + 120 
    5 UIKit        0x000000010e0ec20f -[UIPickerView _delegateNumberOfComponents] + 56 
    6 UIKit        0x000000010e0eb33b -[UIPickerView _updateSelectedRows] + 91 
    7 UIKit        0x000000010e0eb40a -[UIPickerView didMoveToWindow] + 102 
    8 UIKit        0x000000010e1cb256 -[UIView(Internal) _didMoveFromWindow:toWindow:] + 1799 
    9 UIKit        0x000000010e1cae82 -[UIView(Internal) _didMoveFromWindow:toWindow:] + 819 
    10 UIKit        0x000000010e1cae82 -[UIView(Internal) _didMoveFromWindow:toWindow:] + 819 
    11 UIKit        0x000000010e1bdfea __45-[UIView(Hierarchy) _postMovedFromSuperview:]_block_invoke + 151 
    12 UIKit        0x000000010e1bded8 -[UIView(Hierarchy) _postMovedFromSuperview:] + 857 
    13 UIKit        0x000000010e1cde56 -[UIView(Internal) _addSubview:positioned:relativeTo:] + 1982 
    14 UIKit        0x000000010e1bc0d7 -[UIView(Hierarchy) addSubview:] + 838 
    15 UIKit        0x000000010e5d0fdb -[UINavigationTransitionView transition:fromView:toView:] + 645 
    16 UIKit        0x000000010e2f095b -[UINavigationController _startTransition:fromViewController:toViewController:] + 3314 
    17 UIKit        0x000000010e2f0ef9 -[UINavigationController _startDeferredTransitionIfNeeded:] + 874 
    18 UIKit        0x000000010e2f1fdb -[UINavigationController __viewWillLayoutSubviews] + 58 
    19 UIKit        0x000000010e4e8dd7 -[UILayoutContainerView layoutSubviews] + 223 
    20 UIKit        0x000000010e1d1ab8 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 1237 
    21 QuartzCore       0x000000011368bbf8 -[CALayer layoutSublayers] + 146 
    22 QuartzCore       0x000000011367f440 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 366 
    23 QuartzCore       0x000000011367f2be _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 24 
    24 QuartzCore       0x000000011360d318 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 280 
    25 QuartzCore       0x000000011363a3ff _ZN2CA11Transaction6commitEv + 475 
    26 QuartzCore       0x000000011363ad6f _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 113 
    27 CoreFoundation      0x000000010dc8d267 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23 
    28 CoreFoundation      0x000000010dc8d1d7 __CFRunLoopDoObservers + 391 
    29 CoreFoundation      0x000000010dc718a6 CFRunLoopRunSpecific + 454 
    30 UIKit        0x000000010e106aea -[UIApplication _run] + 434 
    31 UIKit        0x000000010e10cc68 UIApplicationMain + 159 
    32 BuzTransit       0x000000010cdb5bbf main + 111 
    33 libdyld.dylib      0x0000000114ce368d start + 1 
) 
libc++abi.dylib: terminating with uncaught exception of type NSException 
(lldb) 

EDIT 2

我已連接我的選擇器的View Controller正確了。

但我覺得我的pickerView仍然沒有正確連接。注意下面的圖片，我猜測圓圈應該用一個胖點標記。正如我所說的從選取器拖到ViewController.swift只是不起作用。

EDIT 4

我不得不重新啓動Xcode和提及的ViewController的名字我的故事板。這兩件事我可以拖放一個IBOutlet從我的故事板到視圖控制器。最後，我的ViewController中連接了一個FAT DOT的圓圈。

Answer 1

點擊助理編輯按鈕，並確保該故事板是在左窗格中和ViewController.swift是正確的。

然後按住control並單擊故事板中的UIPickerView元素，然後將鼠標拖到右側。將它放在類ViewController和重載func viewDidLoad之間。

一個小對話框會彈出來問你這個IBOutlet中屬性的名稱。只是將其命名爲「選擇器」。

這樣做之後，你的ViewController.swift文件將是這樣的：

在ViewController.swift，添加以下代碼。

class ViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource { 

    @IBOutlet weak var picker: UIPickerView! 

var pickerDataSource: [String] = [String]() 

override func viewDidLoad() { 
    super.viewDidLoad() 
    // Do any additional setup after loading the view, typically from a nib. 

    // Connect data: 
    self.picker.delegate = self 
    self.picker.dataSource = self 

    // Input data into the Array: 
    pickerDataSource = ["White", "Red", "Green", "Blue"] 
} 

然後連接數據源和委託

// Methods for Country Code pickerView 
func numberOfComponents(in pickerView: UIPickerView) -> Int { 
    return 1 
} 

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

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

樣品就可以得到tutorial here

更新錯誤狀態

**終止，由於應用程序未捕獲的異常「NSInvalidArgumentException」，原因是：「 - [UIView的numberOfComponentsInPickerView：]：無法識別的選擇發送到實例0x7faa3a40a900」

答：這意味着沒有正確連接到當前類的選擇器視圖。

連接錯誤

你是連接查看

正確的是你需要與你的文件的所有者連接