Delphi IOS Background 之 Background Fetch

http://stackoverflow.com/questions/32348081/delphi-firemonkey-ios-background-processing

I finally got it to work under delphi 10 Seattle (you need this version, i have tried XE7 and doesn't work, I haven't tried xe8). Here are the steps:

Project > Options > Version Info. Check UIBackgroundModes you need (I used Fetch)

1。设置setMinimumBackgroundFetchInterval时间间隔

2.实现performFetchWithCompletionHandler方法

unit uBackgroundiOS;

interface

uses fmx.platform.iOS,iOSapi.CocoaTypes, Macapi.ObjCRuntime, Macapi.ObjectiveC,
     iOSapi.UIKit;

const
  UIBackgroundFetchResultNewData:NSUInteger = 0;
  UIBackgroundFetchResultNoData:NSUInteger = 1;
  UIBackgroundFetchResultFailed:NSUInteger = 2;

  UIApplicationBackgroundFetchIntervalMinimum:NSTimeInterval = 0;
  UIApplicationBackgroundFetchIntervalNever:NSTimeInterval = -1;

type

  // copied from fmx.platform.iOS as it's on private declaration
  id = Pointer;
  SEL = Pointer;
  PUIApplication = Pointer;

  IMP = function( self : id; cmd : SEL; Param1 : NSUInteger ) : id; cdecl;

  function imp_implementationWithBlock( block :id ) : IMP; cdecl; external libobjc name  _PU + 'imp_implementationWithBlock';
  function imp_removeBlock( anImp : IMP ) : integer; cdecl; external libobjc name _PU + 'imp_removeBlock';

  procedure performFetchWithCompletionHandler(self : id; _cmd : SEL; application:    PUIApplication; handler : id );

  procedure initializeBackgroundFetch;

  function objc_msgSend(theReceiver: Pointer; theSelector: Pointer): Pointer; cdecl; varargs;
  external libobjc name _PU + 'objc_msgSend';

  //to test if procedure is called in background
  var fecth_string_test: string;

implementation

procedure performFetchWithCompletionHandler(self : id; _cmd : SEL; application: PUIApplication; handler : id );
var
  ahandlerimp: IMP;
begin
  //Code to perform fetch HERE!!!!
  fecth_string_test := 'entered background code!!';
  surl:='www.cnblog.com/abc/123.html';
  ahandlerimp := imp_implementationWithBlock( handler ); //Create c function for block
  ahandlerimp(self,_cmd, UIBackgroundFetchResultNewData); //Call c function, _cmd is ignored 接收到的新数据
  imp_removeBlock(ahandlerimp); //Remove the c function created two lines up

end;

procedure initializeBackgroundFetch;
Var
  UIApp: UIApplication;
begin
  UIApp := TUIApplication.Wrap(TUIApplication.OCClass.sharedApplication);

  objc_msgSend((UIApp as ILocalObject).GetObjectId,
                sel_getUid('setMinimumBackgroundFetchInterval:'),
                UIApplicationBackgroundFetchIntervalMinimum);

  class_addMethod(objc_getClass('DelphiAppDelegate') ,
                  sel_getUid('application:performFetchWithCompletionHandler:'),
                  @performFetchWithCompletionHandler,
                  'v@:@?');
end;

end.

也可以在didFinishLaunchingWithOptions事件里设置UIApplicationBackgroundFetchIntervalMinimum时间

执行完了要调用completionHandler告知系统。

[[UIApplication sharedApplication] setMinimumBackgroundFetchInterval:UIApplicationBackgroundFetchIntervalMinimum];

performFetchWithCompletionHandler是回调函数，可以在里边写个通知！
http://www.cnblogs.com/skinWalkers/p/3730118.html

讲的好！
http://www.cnblogs.com/zanglitao/p/4113283.html

performFetchWithCompletionHandler Declaration

Swift

optional func application(_ application: UIApplication,

performFetchWithCompletionHandler completionHandler: (UIBackgroundFetchResult) -> Void)

Objective-C

- (void)application:(completionHandler

Parameters