我一直尝试在我的应用程序中实现输入附件 VC，但遇到了以下问题。当我尝试修改自定义 UIInputViewController 的根视图的高度时，尽管存在一个问题，但它运行良好。问题是在日志中我看到以下内容：
[LayoutConstraints] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want.
Try this:
(1) look at each constraint and try to figure out which you don't expect;
(2) find the code that added the unwanted constraint or constraints and fix it.
(Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
<NSAutoresizingMaskLayoutConstraint:0x174490cc0 UIInputView:0x10a80bb80.(null) == 46.5>,
<NSAutoresizingMaskLayoutConstraint:0x17448cd50 UIInputView:0x10a80bb80.height == 76>,
<NSLayoutConstraint:0x17429b710 UIInputView:0x10a80bb80.top == UIInputSetHostView:0x10402e940.top>
)
Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x17429b710 UIInputView:0x10a80bb80.top == UIInputSetHostView:0x10402e940.top>
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.
我的自定义 UIInputViewController 的代码：
import UIKit
import RxSwift
import RxCocoa
@objc protocol InputViewControllerDelegate: NSObjectProtocol {
func answerTextViewDidChange(_ textView: UITextView)
}
class InputViewController: UIInputViewController {
fileprivate var closeButton: UIButton?
private var separatorView: UIView?
private var tipLabel: UILabel?
private var answerTextView: ConstrainedTextView?
private var buttonHeightConstraint: NSLayoutConstraint?
private var separatorHeightConstraint: NSLayoutConstraint?
private var answerTextViewBottomConstraint: NSLayoutConstraint?
weak var delegate: InputViewControllerDelegate?
private let junk = DisposeBag()
private var appropriateMaxLines: Int {
let isPortrait = UIDevice.current.orientation.isPortrait
return isPortrait ? 5 : 3
}
var answerText: String {
get {
return answerTextView?.text ?? ""
}
set {
answerTextView?.text = newValue
}
}
var isAnswerTextViewFirstResponder: Bool {
get {
return answerTextView?.isFirstResponder ?? false
}
set {
_ = newValue ? answerTextView?.becomeFirstResponder() : answerTextView?.resignFirstResponder()
}
}
// MARK: - Life Cycle
deinit {
NotificationCenter.default.removeObserver(self)
}
override func loadView() {
super.loadView()
let notifName = Notification.Name.UIDeviceOrientationDidChange
NotificationCenter.default.addObserver(self,
selector: #selector(rotated),
name: notifName,
object: nil)
configureView()
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
answerTextView?.maxLines = appropriateMaxLines
setCloseButtonDisabledIfNeeded()
}
// MARK: - Layout
private func configureView() {
view.backgroundColor = RGB(0xF6F6F6)
view.frame = CGRect(x: 0, y: 0, width: screenWidth, height: 70)
view.autoresizingMask = [.flexibleWidth]
// Separator
separatorView = UIView()
separatorView?.backgroundColor = UIColor.lightGray
separatorView?.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(separatorView!)
AutoLayoutEqualizeSuper(separatorView, .left, 0)
AutoLayoutEqualizeSuper(separatorView, .right, 0)
AutoLayoutEqualizeSuper(separatorView, .top, 0)
separatorHeightConstraint = AutoLayoutSetAttribute(separatorView, .height, 1)
// Close Button
closeButton = UIButton(type: .system)
closeButton?.setTitle("Hide", for: .normal)
closeButton?.titleLabel?.font = UIFont.systemFont(ofSize: 17)
closeButton?.translatesAutoresizingMaskIntoConstraints = false
closeButton?.addTarget(self, action: #selector(dismissKeyboard), for: .touchUpInside)
view.addSubview(closeButton!)
AutoLayoutSetAttribute(closeButton, .width, 70)
buttonHeightConstraint = AutoLayoutSetAttribute(closeButton, .height, 35)
AutoLayoutEqualizeSuper(closeButton, .right, -5)
view.addConstraint(NSLayoutConstraint(item: closeButton!, attribute: .top, relatedBy: .equal, toItem: separatorView, attribute: .bottom, multiplier: 1, constant: 0))
// Tip Label
tipLabel = UILabel()
tipLabel?.textColor = UIColor.darkGray
tipLabel?.text = "Your answer:"
tipLabel?.font = UIFont.systemFont(ofSize: 17)
tipLabel?.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(tipLabel!)
AutoLayoutEqualizeSuper(tipLabel, .left, 5)
AutoLayoutSetAttribute(tipLabel, .height, 35)
view.addConstraint(NSLayoutConstraint(item: tipLabel!, attribute: .right, relatedBy: .equal, toItem: closeButton, attribute: .left, multiplier: 1, constant: 0))
// Text View
answerTextView = ConstrainedTextView()
answerTextView?.backgroundColor = UIColor.white
answerTextView?.delegate = self
answerTextView?.scrollsToTop = false
answerTextView?.showsVerticalScrollIndicator = false
answerTextView?.font = REG_FONT(15)
answerTextView?.translatesAutoresizingMaskIntoConstraints = false
answerTextView?.layer.masksToBounds = true
answerTextView?.layer.cornerRadius = 7
answerTextView?.layer.borderColor = UIColor.lightGray.withAlphaComponent(0.7).cgColor
answerTextView?.layer.borderWidth = 1
view.addSubview(answerTextView!)
AutoLayoutEqualizeSuper(answerTextView, .left, 5)
AutoLayoutEqualizeSuper(answerTextView, .right, -5)
answerTextViewBottomConstraint = AutoLayoutEqualizeSuper(answerTextView, .bottom, -5)
answerTextView?
.rx
.observe(CGRect.self, "bounds")
.distinctUntilChanged {
$0?.height == $1?.height
}
.subscribe(onNext: { [unowned self] newBounds in
if var newHeight = newBounds?.height,
let separatorHeight = self.separatorHeightConstraint?.constant,
let buttonHeight = self.buttonHeightConstraint?.constant,
let bottomSpace = self.answerTextViewBottomConstraint?.constant {
newHeight = newHeight < 35 ? 35 : newHeight
let generalHeight = newHeight + separatorHeight + buttonHeight + abs(bottomSpace)
var frame = self.view.frame
frame.size.height = generalHeight
self.view.frame = frame
}
})
.addDisposableTo(junk)
}
// MARK: - Other methods
fileprivate func setCloseButtonDisabledIfNeeded() {
closeButton?.isEnabled = answerTextView?.isFirstResponder ?? false
}
func rotated() {
answerTextView?.maxLines = appropriateMaxLines
}
}
// MARK: - UITextViewDelegate Protocol Conformance
extension InputViewController: UITextViewDelegate {
func textViewShouldBeginEditing(_ textView: UITextView) -> Bool {
textView.inputAccessoryView = view
return true
}
func textViewShouldEndEditing(_ textView: UITextView) -> Bool {
textView.inputAccessoryView = nil
return true
}
func textViewDidBeginEditing(_ textView: UITextView) {
setCloseButtonDisabledIfNeeded()
}
func textViewDidEndEditing(_ textView: UITextView) {
setCloseButtonDisabledIfNeeded()
}
func textViewDidChange(_ textView: UITextView) {
delegate?.answerTextViewDidChange(textView)
}
}