Собственный сценарий: делегат, расширяющий броски NSObject Ошибка: это значение не является собственным объектом

Question

Я пытаюсь создать делегат события прокрутки для ListView на iOS, основываясь на следующем примере кода: https://github.com/NativeScript/NativeScript/issues/2521#issuecomment-306447460

(реализация Android работает как чемпион. IOS рушится эпическим способом)

При выполнении функции new выдается фатальная ошибка.

Делегирование

class ScrollingUITableViewDelegateImpl extends NSObject implements UITableViewDelegate {

    private _originalDelegate: UITableViewDelegate;

    static ObjCProtocols = [UITableViewDelegate]; 

    static new():ScrollingUITableViewDelegateImpl {
      return <ScrollingUITableViewDelegateImpl>super.new();
    }

    static initWithOrigDelegate(original: UITableViewDelegate): ScrollingUITableViewDelegateImpl {
        const delegate = <ScrollingUITableViewDelegateImpl>ScrollingUITableViewDelegateImpl.new();
        delegate._originalDelegate = original;
        return delegate;
    }

    /* OriginalDelegate items */
    public tableViewWillDisplayCellForRowAtIndexPath(tableView: UITableView, cell: UITableViewCell, indexPath: NSIndexPath) {
      return this._originalDelegate.tableViewWillDisplayCellForRowAtIndexPath(tableView, cell, indexPath)
    }
    public tableViewWillSelectRowAtIndexPath(tableView: UITableView, indexPath: NSIndexPath): NSIndexPath {
      return this._originalDelegate.tableViewWillSelectRowAtIndexPath(tableView, indexPath);
    }
    public tableViewDidSelectRowAtIndexPath(tableView: UITableView, indexPath: NSIndexPath): NSIndexPath {
      tableView.deselectRowAtIndexPathAnimated(indexPath, true);
      return indexPath;
    }
    public tableViewHeightForRowAtIndexPath(tableView: UITableView, indexPath: NSIndexPath): number {
      return this._originalDelegate.tableViewHeightForRowAtIndexPath(tableView, indexPath);
    }

    /* Scroll Delegate items */
    public scrollViewWillBeginDragging(scrollView:UIScrollView) {
        console.log('willbegindragging');
    }
    public scrollViewDidScroll(scrollView:UIScrollView) {
        console.log('didscroll');
    }
}

Error

***** Fatal JavaScript exception - application has been terminated. *****
Native stack trace:
1   0x100aa373c 
NativeScript::reportFatalErrorBeforeShutdown(JSC::ExecState*, JSC::Exception*, bool, bool)
2   0x100ac92e4 NativeScript::FFICallback<NativeScript::ObjCMethodCallback>::ffiClosureCallback(ffi_cif*, void*, void**, void*)
3   0x1013cb088 ffi_closure_SYSV_inner
4   0x1013cc1b4 .Ldo_closure
5   0x1b211ea60 <redacted> 
6   0x1b211f144 <redacted>
7   0x1b20860e8 <redacted>
8   0x1b2086da8 <redacted>
9   0x1b20880a8 <redacted>
10  0x1b206a298 <redacted>
11  0x1b2b7ff44 <redacted>
12  0x18a13da34 <redacted>
13  0x18a1429c4 <redacted>
14  0x18a0a19d4 <redacted>
15  0x18a0d02f4 <redacted>
16  0x1b26f736c <redacted>
17  0x185aea408 <redacted>
18  0x185ae9d08 <redacted>
19  0x185ae4cfc <redacted>
20  0x185ae45b8 CFRunLoopRunSpecific
21  0x187d58584 GSEventRunModal
22  0x1b26dcbc8 UIApplicationMain
23  0x1013cc044 ffi_call_SYSV
24  0x1013ca7a4 ffi_call_int
25  0x1013ca26c ffi_call
26  0x100a81630 NativeScript::FFICall::call(JSC::ExecState*)
27  0x10107ce14 JSC::LLInt::setUpCall(JSC::ExecState*, JSC::Instruction*, JSC::CodeSpecializationKind, JSC::JSValue, JSC::LLIntCallLinkInfo*)
28  0x101085a24 llint_entry
29  0x101085a34 llint_entry
30  0x101085a34 llint_entry
31  0x10107eee0 vmEntryToJavaScript
JavaScript stack trace:
1   new@file:///app/components/scroll-list-view/scroll-list-view.js:10:25
2   new@file:///app/components/scroll-list-view/scroll-list-view.js:10:25
3   initWithOrigDelegate@file:///app/components/scroll-list-view/scroll-list-view.js:13:59
4   initNativeView@file:///app/components/scroll-list-view/scroll-list-view.js:46:76
5   setNativeView@file:///app/tns_modules/tns-core-modules/ui/core/view-base/view-base.js:548:32
6   _setupUI@file:///app/tns_modules/tns-core-modules/ui/core/view-base/view-base.js:527:27
7   @file:///app/tns_modules/tns-core-modules/ui/core/view-base/view-base.js:534:27
8   eachChildView@file:///app/tns_modules/tns-core-modules/ui/layouts/layout-base-common.js:125:34
9   eachChild@file:///app/tns_modules/tns-core-modules/ui/core/view/view-common.js:868:27
10  _setupUI@file:///app/tns_modules/tns-core-modules/ui/core/view-base/view-base.js:533:23
11  @file:///app/tns_modules/tns-core-modules/ui/core/view-base/view-base.js:534:27
12  eachChildView@file:///app/tns_modules/tns-core-mo<\M-b\M^@\M-&>
JavaScript error:
file:///app/components/scroll-list-view/scroll-list-view.js:10:25: JS ERROR Error: This value is not a native object.
*** JavaScript call stack:
(
0   UIApplicationMain@[native code]
1   start@file:///app/tns_modules/tns-core-modules/application/application.js:272:26
2   run@file:///app/tns_modules/tns-core-modules/application/application.js:300:10
3   anonymous@file:///app/app.js:20:16
4   evaluate@[native code]
5   moduleEvaluation@:1:11
6   @:7:48
7   promiseReactionJob@:1:11
)
*** Terminating app due to uncaught exception****
 'NativeScript encountered a fatal error: Error: This value is not a native object.
at
1   new@file:///app/components/scroll-list-view/scroll-list-view.js:10:25
2   new@file:///app/components/scroll-list-view/scroll-list-view.js:10:25
3   initWithOrigDelegate@file:///app/components/scroll-list-view/scroll-list-view.js:13:59
4   initNativeView@file:///app/components/scroll-list-view/scroll-list-view.js:46:76
5   setNativeView@file:///app/tns_modules/tns-core-modules/ui/core/view-base/view-base.js:548:32
6   _setupUI@file:///app/tns_modules/tns-core-modules/ui/core/view-base/view-base.js:527:27
7   @file:///app/tns_modules/tns-core-modules/ui/core/view-base/view-base.js:534:27
8   eachChildView@file:///app/tns_modules/tns-core-modules/ui/layouts/layout-base-common.js:125:34
9   eachChild@file:///app/tns_modules/tns-core-modules/ui/core/view/view-common.js:868:27
10  _setupUI@file:///app/tns_modules/tns-core-modules/ui/core/view-base/view-base.js:533:23
11 <\M-b\M^@\M-&>

UPDATE Новый код

var ScrollingUITableViewDelegateImpl = (NSObject as any).extend({
_originalDelegate: null,

/* OriginalDelegate items */
tableViewWillDisplayCellForRowAtIndexPath(tableView: UITableView, cell: UITableViewCell, indexPath: NSIndexPath) {
    if (this._originalDelegate) 
      return this._originalDelegate.tableViewWillDisplayCellForRowAtIndexPath(tableView, cell, indexPath)
    return null;
},
tableViewWillSelectRowAtIndexPath(tableView: UITableView, indexPath: NSIndexPath): NSIndexPath {
   if (this._originalDelegate) 
     return this._originalDelegate.tableViewWillSelectRowAtIndexPath(tableView, indexPath);
   return null;
  },
tableViewDidSelectRowAtIndexPath(tableView: UITableView, indexPath: NSIndexPath): NSIndexPath {
    tableView.deselectRowAtIndexPathAnimated(indexPath, true);
    return indexPath;
},
tableViewHeightForRowAtIndexPath(tableView: UITableView, indexPath: NSIndexPath): number {
    if (this._originalDelegate) 
      return this._originalDelegate.tableViewHeightForRowAtIndexPath(tableView, indexPath);
    return null;
},

/* Scroll Delegate items */
scrollViewWillBeginDragging(scrollView:ScrollListView) {
  if (this._originalDelegate) {
    const owner:ListView = (this._originalDelegate['_owner'] as WeakRef<ListView>).get();
    owner.notify({eventName: ScrollListViewBase.ScrollEvent, object: owner});
  }
  else { console.log('no delegate'); }
},
scrollViewDidScroll(scrollView:ScrollListView) {
  if (this._originalDelegate) {
    const owner:ListView = (this._originalDelegate['_owner'] as WeakRef<ListView>).get();
    owner.notify({eventName: ScrollListViewBase.ScrollStateChangedEvent, object: owner});
  }
  else { console.log('no delegate'); }
}
}, {
   name: 'ScrollingUITableViewDelegateImpl',
   protocols: [UITableViewDelegate],
});

Обновленный код запускается, но я сталкиваюсь с новой ошибкой: JavaScript error: file:///app/tns_modules/tns-core-modules/ui/core/view/view-common.js:794:21: JS ERROR TypeError: child.layout is not a function. (In 'child.layout(childLeft, childTop, childRight, childBottom, setFram( 0 UIApplicationMain@[native code] 1 start@file:///app/tns_modules/tns-core-modules/application/application.js:272:26 2 run@file:///app/tns_modules/tns-core-modules/application/application.js:300:10 3 anonymous@file:///app/app.js:20:16 4 evaluate@[native code] 5 moduleEvaluation@:1:11 6 @:7:48 7 promiseReactionJob@:1:11 )

Answer 1

Я не думаю, что эти строки действительны и не обязательны.

static new():ScrollingUITableViewDelegateImpl {
  return <ScrollingUITableViewDelegateImpl>super.new();
}

1. Это статический метод, и супер даже не будет доступен здесь.
2. Это метод по умолчанию, реализованный в NSObject, вам не нужно реализовывать его снова, поскольку вы расширяете его

Answer 2

разрешил его, используя метод extend (исключая es2015 class B extends A и статические функции), например:

import { ListView } from "tns-core-modules/ui/list-view/list-view";
import { ScrollListViewBase } from './scroll-list-view-common';
import { Length, View } from "tns-core-modules/ui/page/page";

export * from 'tns-core-modules/ui/list-view';

var ScrollingUITableViewDelegateImpl = (NSObject as any).extend({
  _originalDelegate: null,
  _owner: null,

  /* OriginalDelegate items */
  tableViewWillDisplayCellForRowAtIndexPath(tableView: UITableView, cell: UITableViewCell, indexPath: NSIndexPath) {
    if (this._originalDelegate) 
      return this._originalDelegate.tableViewWillDisplayCellForRowAtIndexPath(tableView, cell, indexPath)
    return null;
  },
  tableViewWillSelectRowAtIndexPath(tableView: UITableView, indexPath: NSIndexPath): NSIndexPath {
    if (this._originalDelegate) 
      return this._originalDelegate.tableViewWillSelectRowAtIndexPath(tableView, indexPath);
    return null;
  },
  tableViewDidSelectRowAtIndexPath(tableView: UITableView, indexPath: NSIndexPath): NSIndexPath {
    tableView.deselectRowAtIndexPathAnimated(indexPath, true);
    return indexPath;
  },
  tableViewHeightForRowAtIndexPath(tableView: UITableView, indexPath: NSIndexPath): number {
    if (this._originalDelegate) 
      return this._originalDelegate.tableViewHeightForRowAtIndexPath(tableView, indexPath);
    return null;
  },

  /* Scroll Delegate items */
  scrollViewWillBeginDragging(scrollView:UIScrollView) {
    this._owner.notify({eventName: ScrollListViewBase.ScrollEvent, object: this._owner});
  },
  scrollViewWillEndDragging(scrollView:UIScrollView, withVelocity: CGPoint, 
    targetContentOffset: CGPoint) {
    this._owner.notify({eventName: ScrollListViewBase.ScrollEvent, object: this._owner});
  },
  scrollViewDidScroll(scrollView:UIScrollView) {
    this._owner.notify({eventName: ScrollListViewBase.ScrollEvent, object: this._owner});
  }
}, {
  protocols: [UITableViewDelegate],
});


export class ScrollListView extends ScrollListViewBase {
  /**
   * Variable __delegate
   *  The ios implementation of Nativescript `ListView` has a private var `_delegate`.
   *  That is being overridden here with the `property _delegate` that wraps 
   *  the original delegate in one that provides scroll event listeners.
   * 
   * This is hackish, but works well.
   */
  private __delegate: UITableViewDelegate;

  get _delegate():UITableViewDelegate { return this.__delegate; }
  set _delegate(v:UITableViewDelegate) {
    if (v == null) {
      this.__delegate = null;
    }
    else {
      const newDelegate = ScrollingUITableViewDelegateImpl.new();
      newDelegate._originalDelegate = v;
      newDelegate._owner = this;
      this.__delegate = newDelegate;
    }
  }
}

Answer 3

Я думаю, вам может понадобиться использовать более старый метод расширения классов, как показано здесь . Например, ваш делегат может выглядеть так:

const ScrollingUITableViewDelegateImpl = (NSObject as any).extend({

  tableViewWillDisplayCellForRowAtIndexPath: function(tableView: UITableView, cell: UITableViewCell, indexPath: NSIndexPath) {
    // ... method implementation here
  }

  // ... more methods here

}, {
  protocols: [ UITableViewDelegate ]
});

const instance = new ScrollingUITableViewDelegateImpl();