我目前正在为IOS制作一个带有Monotouch框架的应用程序，该框架有一个UITableView和一个包含UISwitch的自定义UITableViewCell（使用XCode设计）。
我通过UITableViewSource管理单元格，但在管理对分配给单元格开关的事件UISwitch.ValueChanged的委托方法的回调时，我显然遇到了问题。
以下是我正在编写的UITableViewSource代码，它可能更明确：
// This class manages the TableView content and its rows
class MyTableViewDelegate : UITableViewSource
{
SatellitesViewController satController;
List<long> allocatedCells;
public MyTableViewDelegate (SatellitesViewController controller)
{
satController = controller;
allocatedCells = new List<long>();
}
public override int RowsInSection (UITableView tableview, int section)
{
return satController.sats.Count;
}
// Called when the switch to show the satellite's display state is touched
public void showButtonHandler(object sender, EventArgs e)
{
System.Console.WriteLine("SHOW BUTTONHANDLER");
if (sender != null)
{
CustomSwitch switchButton = (CustomSwitch) sender;
TLEForRedis satToShow = this.satController.getSatTLEs(switchButton.idSat, false);
if (satToShow != null)
{
if (switchButton.On == true)
this.satController.glView.showSatellite(satToShow);
else
this.satController.glView.hideSatellite(satToShow.Id);
}
}
}
// Called when the switch to show the satellite's display state is touched
public void orbitButtonHandler(object sender, EventArgs e)
{
System.Console.WriteLine("ORBIT BUTTONHANDLER");
if (sender != null)
{
CustomSwitch orbitButton = (CustomSwitch) sender;
TLEForRedis satToShow = this.satController.getSatTLEs(orbitButton.idSat, false);
if (satToShow != null)
this.satController.glView.setSatelliteOrbitDisplayState(satToShow.Id, orbitButton.On);
}
}
// Create the cell at indexPath
public override UITableViewCell GetCell (UITableView tableView, NSIndexPath indexPath)
{
string cellName;
string nibName;
cellName = "PROTO_CELL";
nibName = "CellView";
// Get the table cell which is described in the CellView.xib interface
var cell = tableView.DequeueReusableCell(cellName) as CellView;
if (cell == null)
{
cell = new CellView();
var views = NSBundle.MainBundle.LoadNib(nibName, cell, null);
cell = Runtime.GetNSObject( views.ValueAt(0) ) as CellView;
}
// Modify the cell with its own data
SatsList sat = (SatsList) satController.sats [indexPath.Row];
CustomSwitch showButton = (CustomSwitch)cell.ViewWithTag(1);
UILabel satName = (UILabel)cell.ViewWithTag(2);
UILabel catalogNumber = (UILabel)cell.ViewWithTag(3);
CustomSwitch favoriteButton = (CustomSwitch)cell.ViewWithTag(4);
CustomSwitch orbitButton = (CustomSwitch)cell.ViewWithTag(5);
UIColor lightgrey = new UIColor(0.85f, 0.85f, 0.85f, 1.0f);
tableView.BackgroundColor = lightgrey;
if (sat != null)
{
satName.Text = sat.satName;
catalogNumber.Text = string.Format("{0}", sat.catalogNumber);
}
else
System.Console.WriteLine("[ERROR] Satellite was not found for row " + indexPath.Row);
// Set switch state to on when the satellite is already being displayed
if (this.satController.glView.checkForSatelliteExistency(sat.Id))
{
System.Console.WriteLine(sat.satName + "found");
showButton.SetState(true, false);
Satellite sat3D = this.satController.glView.checkForSatelliteOrbit(sat.Id);
if (sat3D.displayOrbit())
orbitButton.SetState(true, false);
}
else // force switch state to off when satellite is not displayed yet
{
showButton.SetState(false, false);
orbitButton.SetState(false, false);
}
favoriteButton.SetState(false, false);
// Bind changing state switches' events in order to display or hide the corresponding satellite
showButton.setData(sat.Id);
favoriteButton.setData(sat.Id);
orbitButton.setData(sat.Id);
if (!this.allocatedCells.Contains(indexPath.Row))
{
showButton.ValueChanged += this.showButtonHandler;
orbitButton.ValueChanged += this.orbitButtonHandler;
}
this.allocatedCells.Add(indexPath.Row);
return cell;
}
}
事实上，上面代码的结果是，我可以在tableView中上下滚动，而不会出现问题，甚至可以打印"SHOW BUTTONHANDLER"一行，直到我没有通过滚动点击已经离开屏幕的开关。但是，当我点击一个开关，这个开关是之前在列表顶部绘制的单元格的一部分，并且在我滚动回顶部后再次出现时，我会得到以下错误：
[7864:1507] -[UIControlTargetAction BridgeSelector]: unrecognized selector sent to instance 0x14462a70
或以下堆栈跟踪：
Stacktrace:
at (wrapper managed-to-native) MonoTouch.UIKit.UIApplication.UIApplicationMain (int,string[],intptr,intptr) <IL 0x0009f, 0xffffffff>
at MonoTouch.UIKit.UIApplication.Main (string[],string,string) [0x00042] in /Developer/MonoTouch/Source/monotouch/src/UIKit/UIApplication.cs:29
at App.Application.Main (string[]) [0x0001b] in App/Main.cs:24
at (wrapper runtime-invoke) <Module>.runtime_invoke_void_object (object,intptr,intptr,intptr) <IL 0x00050, 0xffffffff>
Native stacktrace:
0 App 0x0009094c mono_handle_native_sigsegv + 284
1 App 0x00005cd8 mono_sigsegv_signal_handler + 248
2 libSystem.B.dylib 0x90d9c05b _sigtramp + 43
3 ??? 0xffffffff 0x0 + 4294967295
4 UIKit 0x0222e55a -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 61
5 UIKit 0x022d3b76 -[UIControl sendAction:to:forEvent:] + 66
6 UIKit 0x022d403f -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 503
7 UIKit 0x02425a6c -[_UISwitchInternalView _sendActions] + 121
8 Foundation 0x0173786d __NSFireDelayedPerform + 389
9 CoreFoundation 0x01195966 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 22
10 CoreFoundation 0x01195407 __CFRunLoopDoTimer + 551
11 CoreFoundation 0x010f87c0 __CFRunLoopRun + 1888
12 CoreFoundation 0x010f7db4 CFRunLoopRunSpecific + 212
13 CoreFoundation 0x010f7ccb CFRunLoopRunInMode + 123
14 GraphicsServices 0x04789879 GSEventRunModal + 207
15 GraphicsServices 0x0478993e GSEventRun + 114
16 UIKit 0x0222ba9b UIApplicationMain + 1175
17 ??? 0x0ebdde65 0x0 + 247324261
18 ??? 0x0ebdc550 0x0 + 247317840
19 ??? 0x0b7f7bac 0x0 + 192904108
20 ??? 0x0b7f7d86 0x0 + 192904582
21 App 0x0000a042 mono_jit_runtime_invoke + 722
22 App 0x00169f4e mono_runtime_invoke + 126
23 App 0x0016e034 mono_runtime_exec_main + 420
24 App 0x00173455 mono_runtime_run_main + 725
25 App 0x00067245 mono_jit_exec + 149
26 App 0x002116a5 main + 2837
27 App 0x00003095 start + 53
28 ??? 0x00000004 0x0 + 4
=================================================================
Got a SIGSEGV while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries
used by your application.
=================================================================
那么，你有解决方案的想法吗？开关的委托方法似乎注册不正确，但我不知道出了什么问题。因为我也在没有的情况下尝试过
if (!this.allocatedCells.Contains(indexPath.Row))
行，以便只注册一次委托，但结果相同。如果单元格离开屏幕并尝试"注销"委托，我需要删除它吗？
我希望你有一个想法，不要犹豫，发表你对这一切的意见/建议/评论。
提前感谢！
好的，我发现我的代码有问题，这是由于绑定到开关的委托造成的。事实上，我忘了注销要离开屏幕的单元格的委派。取消ReusableCell的标题并不会删除链接到单元格内容的委托=>这导致使用引用已更改的发件人调用我的showButtonHandler（sender，args）方法。
因此，我的代码的解决方案是将最后一部分更改为：
// Bind changing state switches' events in order to display or hide the corresponding satellite
showButton.setData(sat.Id);
favoriteButton.setData(sat.Id);
orbitButton.setData(sat.Id);
showButton.ValueChanged -= this.showButtonHandler;
orbitButton.ValueChanged -= this.orbitButtonHandler;
showButton.ValueChanged += this.showButtonHandler;
orbitButton.ValueChanged += this.orbitButtonHandler;
return cell;
}
在我的情况下，甚至没有必要在旧的allocatedCells列表中注册单元格。重新使用单元后，旧委派将从交换机中删除（-=），并用新的新引用替换（+=）。
谢谢大家，不管怎样。