尝试关闭选择器时收到错误

Question

我创建了一个程序，该程序在单击文本字段时显示选择器，并且在我单击工具栏上的“完成”或“取消”按钮时试图将其关闭。

我不知道哪里出了问题。 虽然说

“ 2017-09-28 20：45：27.877897-0600 project1 [51296：5112470] [LayoutConstraints]无法同时满足约束。”

我所有的约束都可以正常工作。

这是我的代码：

@IBOutlet weak var textField1: UITextField!

override func viewDidLoad() {
    super.viewDidLoad()


    let picker: UIPickerView

    picker = UIPickerView(frame: CGRect(x: 0, y: 0, width: view.frame.width, height: 300))
    picker.backgroundColor = .white

    picker.showsSelectionIndicator = true
    picker.delegate = self
    picker.dataSource = self

    let toolBar = UIToolbar(frame: CGRect(x: 0, y: 0, width: view.frame.size.width, height: 40))
    toolBar.barStyle = UIBarStyle.default
    toolBar.isTranslucent = true
    toolBar.tintColor = .black

    let doneButton = UIBarButtonItem(title: "Done", style: UIBarButtonItemStyle.plain, target: self, action:
        Selector(("donePicker")))
    let spaceButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.flexibleSpace, target: nil, action: nil)
    let cancelButton = UIBarButtonItem(title: "Cancel", style: UIBarButtonItemStyle.plain, target: self, action: Selector(("donePicker")))
    )

    toolBar.setItems([cancelButton, spaceButton, doneButton], animated: true)
    toolBar.isUserInteractionEnabled = true

    let bgView = UIView(frame: CGRect(x: 0, y: 0, width: view.frame.width, height: 250 + toolBar.frame.size.height))
    print(picker.frame.size.height, toolBar.frame.size.height, bgView.frame.size.height)


    bgView.addSubview(picker)
    bgView.addSubview(toolBar)
    textField1.inputView = bgView
}

func donePicker() {
    textField1.resignFirstResponder()
}

这是它给我的错误：

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
2017-09-28 20:45:29.253610-0600 project1[51296:5112470] [MC] Lazy loading NSBundle MobileCoreServices.framework
2017-09-28 20:45:29.255001-0600 project1[51296:5112470] [MC] Loaded MobileCoreServices.framework
2017-09-28 20:45:29.274235-0600 project1[51296:5112470] [MC] System group container for systemgroup.com.apple.configurationprofiles path is /Users/Andrew/Library/Developer/CoreSimulator/Devices/EE44EDE5-BDF6-4A15-A44B-387E14685DAA/data/Containers/Shared/SystemGroup/systemgroup.com.apple.configurationprofiles
300.0 44.0 294.0
2017-09-28 20:45:30.401748-0600 project1[51296:5112470] [MC] Reading from private effective user settings.
2017-09-28 20:45:31.827410-0600 project1[51296:5112470] -[project1.CalculateViewController donePicker]: unrecognized selector sent to instance 0x7faac1d0fab0
2017-09-28 20:45:31.835746-0600 project1[51296:5112470] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[project1.CalculateViewController donePicker]: unrecognized selector sent to instance 0x7faac1d0fab0'
*** First throw call stack:
(
    0   CoreFoundation                      0x000000010c8a11cb __exceptionPreprocess + 171
    1   libobjc.A.dylib                     0x000000010a93cf41 objc_exception_throw + 48
    2   CoreFoundation                      0x000000010c921914 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132
    3   UIKit                               0x000000010d4660bd -[UIResponder doesNotRecognizeSelector:] + 295
    4   CoreFoundation                      0x000000010c824178 ___forwarding___ + 1432
    5   CoreFoundation                      0x000000010c823b58 _CF_forwarding_prep_0 + 120
    6   UIKit                               0x000000010d23f9bd -[UIApplication sendAction:to:from:forEvent:] + 83
    7   UIKit                               0x000000010dc3353f __45-[_UIButtonBarTargetAction _invoke:forEvent:]_block_invoke + 154
    8   UIKit                               0x000000010dc33470 -[_UIButtonBarTargetAction _invoke:forEvent:] + 181
    9   UIKit                               0x000000010d23f9bd -[UIApplication sendAction:to:from:forEvent:] + 83
    10  UIKit                               0x000000010d3b6183 -[UIControl sendAction:to:forEvent:] + 67
    11  UIKit                               0x000000010d3b64a0 -[UIControl _sendActionsForEvents:withEvent:] + 450
    12  UIKit                               0x000000010d3b53cd -[UIControl touchesEnded:withEvent:] + 618
    13  UIKit                               0x000000010d2b3d4f -[UIWindow _sendTouchesForEvent:] + 2807
    14  UIKit                               0x000000010d2b5472 -[UIWindow sendEvent:] + 4124
    15  UIKit                               0x000000010d25a802 -[UIApplication sendEvent:] + 352
    16  UIKit                               0x000000010db8ca50 __dispatchPreprocessedEventFromEventQueue + 2809
    17  UIKit                               0x000000010db8f5b7 __handleEventQueueInternal + 5957
    18  CoreFoundation                      0x000000010c8442b1 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
    19  CoreFoundation                      0x000000010c8e3d31 __CFRunLoopDoSource0 + 81
    20  CoreFoundation                      0x000000010c828c19 __CFRunLoopDoSources0 + 185
    21  CoreFoundation                      0x000000010c8281ff __CFRunLoopRun + 1279
    22  CoreFoundation                      0x000000010c827a89 CFRunLoopRunSpecific + 409
    23  GraphicsServices                    0x00000001122ee9c6 GSEventRunModal + 62
    24  UIKit                               0x000000010d23dd30 UIApplicationMain + 159
    25  UofA Engineering Master             0x0000000109ffa307 main + 55
    26  libdyld.dylib                       0x000000010fbc5d81 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb) 

Answer 1

我尝试了另一种方法来在textField显示PickerView和toolbar 。

如果对您的情况有帮助，请尝试以下操作：

let toolBar = UIToolbar()
toolBar.barStyle = UIBarStyle.default
toolBar.isTranslucent = true
toolBar.tintColor = UIColor(red: 76/255, green: 217/255, blue: 100/255, alpha: 1)
toolBar.sizeToFit()

let doneButton = UIBarButtonItem(title: "Done", style: UIBarButtonItemStyle.plain, target: self, action: #selector(CalculateViewController.donePicker))
let spaceButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.flexibleSpace, target: nil, action: nil)
let cancelButton = UIBarButtonItem(title: "Cancel", style: UIBarButtonItemStyle.plain, target: self, action: #selector(CalculateViewController.cancelPicker))

toolBar.setItems([cancelButton, spaceButton, doneButton], animated: false)
toolBar.isUserInteractionEnabled = true

textField1.inputView = pickerView
textField1.inputAccessoryView = toolBar

Answer 2

您可以看到错误消息是：

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[project1.CalculateViewController donePicker]: unrecognized selector sent to instance 0x7faac1d0fab0'

对于Swift，我们不会像这样定义selector （这是Objective C的方式）。 您应该这样使用：

let doneButton = UIBarButtonItem(title: "Done", style: UIBarButtonItemStyle.plain, target: self, action:
    #selector(donePicker))

Answer 3

由于错误是无法识别的选择器发送到实例，因此您可以让选择器变为属性。 用var picker: UIPickerView? viewdidload let picker: UIPickerView取代viewdidload方法中的let picker: UIPickerView viewdidload var picker: UIPickerView?