使用 IFMXImageManagerService 时 iOS 上的访问冲突

Question

我正在使用这个简单的代码：

procedure TForm1.Button1Click(Sender: TObject);
var servicios: IFMXImageManagerService;
    i:integer;
begin
    i:=servicios.GetCount;
    showmessage(inttostr(i));
end;

我收到一条 iOS 消息：“地址 0000000104BB0460 发生访问冲突，访问地址 00000000000000000”。

我对 IFMXImageManagerService 的所有尝试都会触发违规消息。

拜托，有人知道为什么吗？

谢谢！

Answer 1

您没有初始化 servicios 以指向任何有意义的东西，因此当然调用任何方法，如 servicios.GetCount()，都会失败。

您需要使用TPlatformServices.GetPlatformService() or TPlatformServices.SupportsPlatformService()来初始化servicios。这在 Embarcadero 的文档中有解释：

FireMonkey Platform Services

To use a platform service, you must:

Add a reference to the unit where your service is declared, such as FMX.Platform, to your unit.

Call TPlatformServices.SupportsPlatformService with the target platform service as a parameter to determine whether or not the specified platform service is supported at run time.

If SupportsPlatformService returns True, use TPlatformServices.GetPlatformService to access the actual platform service, and cast the returned service appropriately. You can alternatively use SupportsPlatformService to obtain the service as well.

试试这个：

uses
  ..., FMX.Platform, FMX.MediaLibrary;

procedure TForm1.Button1Click(Sender: TObject);
var
  servicios: IFMXImageManagerService;
  i: integer;
begin
  if TPlatformServices.Current.SupportsPlatformService(IFMXImageManagerService, IInterface(servicios)) then
  begin
    i := servicios.GetCount;
    ShowMessage(IntToStr(i));
  end else
    ShowMessage('Image Manager not supported');
end;

使用 IFMXImageManagerService 时 iOS 上的访问冲突

Access Violation on iOS when use IFMXImageManagerService

delphi